diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index 928b80dd9..a42ed25cf 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -65,7 +65,6 @@ use Slic3r::Format::AMF;
 use Slic3r::Format::OBJ;
 use Slic3r::Format::STL;
 use Slic3r::GCode::ArcFitting;
-use Slic3r::GCode::CoolingBuffer;
 use Slic3r::GCode::MotionPlanner;
 use Slic3r::GCode::PressureRegulator;
 use Slic3r::GCode::Reader;
diff --git a/lib/Slic3r/Print/GCode.pm b/lib/Slic3r/Print/GCode.pm
index d7bdcc591..9f0421e45 100644
--- a/lib/Slic3r/Print/GCode.pm
+++ b/lib/Slic3r/Print/GCode.pm
@@ -100,10 +100,7 @@ sub BUILD {
         }
     }
     
-    $self->_cooling_buffer(Slic3r::GCode::CoolingBuffer->new(
-        config      => $self->config,
-        gcodegen    => $self->_gcodegen,
-    ));
+    $self->_cooling_buffer(Slic3r::GCode::CoolingBuffer->new($self->_gcodegen));
     
     $self->_spiral_vase(Slic3r::GCode::SpiralVase->new(config => $self->config))
         if $self->config->spiral_vase;
diff --git a/t/cooling.t b/t/cooling.t
index f39fa0f52..2d76bf747 100644
--- a/t/cooling.t
+++ b/t/cooling.t
@@ -12,20 +12,17 @@ BEGIN {
 use Slic3r;
 use Slic3r::Test;
 
+my $gcodegen;
 sub buffer {
     my $config = shift || Slic3r::Config->new;
     
     my $print_config = Slic3r::Config::Print->new;
     $print_config->apply_dynamic($config);
     
-    my $gcodegen = Slic3r::GCode->new;
+    $gcodegen = Slic3r::GCode->new;
     $gcodegen->apply_print_config($print_config);
     $gcodegen->set_layer_count(10);
-    my $buffer = Slic3r::GCode::CoolingBuffer->new(
-        config      => $print_config,
-        gcodegen    => $gcodegen,
-    );
-    return $buffer;
+    return Slic3r::GCode::CoolingBuffer->new($gcodegen);
 }
 
 my $config = Slic3r::Config->new_from_defaults;
@@ -33,14 +30,14 @@ $config->set('disable_fan_first_layers', 0);
 
 {
     my $buffer = buffer($config);
-    $buffer->gcodegen->set_elapsed_time($buffer->config->slowdown_below_layer_time + 1);
+    $buffer->gcodegen->set_elapsed_time($buffer->gcodegen->config->slowdown_below_layer_time + 1);
     my $gcode = $buffer->append('G1 F3000;_EXTRUDE_SET_SPEED\nG1 X100 E1', 0, 0, 0.4) . $buffer->flush;
     like $gcode, qr/F3000/, 'speed is not altered when elapsed time is greater than slowdown threshold';
 }
 
 {
     my $buffer = buffer($config);
-    $buffer->gcodegen->set_elapsed_time($buffer->config->slowdown_below_layer_time - 1);
+    $buffer->gcodegen->set_elapsed_time($buffer->gcodegen->config->slowdown_below_layer_time - 1);
     my $gcode = $buffer->append(
         "G1 X50 F2500\n" .
         "G1 F3000;_EXTRUDE_SET_SPEED\n" .
@@ -55,7 +52,7 @@ $config->set('disable_fan_first_layers', 0);
 
 {
     my $buffer = buffer($config);
-    $buffer->gcodegen->set_elapsed_time($buffer->config->fan_below_layer_time + 1);
+    $buffer->gcodegen->set_elapsed_time($buffer->gcodegen->config->fan_below_layer_time + 1);
     my $gcode = $buffer->append('G1 X100 E1 F3000', 0, 0, 0.4) . $buffer->flush;
     unlike $gcode, qr/M106/, 'fan is not activated when elapsed time is greater than fan threshold';
 }
@@ -65,7 +62,7 @@ $config->set('disable_fan_first_layers', 0);
     my $gcode = "";
     for my $obj_id (0 .. 1) {
         # use an elapsed time which is < the slowdown threshold but greater than it when summed twice
-        $buffer->gcodegen->set_elapsed_time($buffer->config->slowdown_below_layer_time - 1);
+        $buffer->gcodegen->set_elapsed_time($buffer->gcodegen->config->slowdown_below_layer_time - 1);
         $gcode .= $buffer->append("G1 X100 E1 F3000\n", $obj_id, 0, 0.4);
     }
     $gcode .= $buffer->flush;
@@ -78,7 +75,7 @@ $config->set('disable_fan_first_layers', 0);
     for my $layer_id (0 .. 1) {
         for my $obj_id (0 .. 1) {
             # use an elapsed time which is < the threshold but greater than it when summed twice
-            $buffer->gcodegen->set_elapsed_time($buffer->config->fan_below_layer_time - 1);
+            $buffer->gcodegen->set_elapsed_time($buffer->gcodegen->config->fan_below_layer_time - 1);
             $gcode .= $buffer->append("G1 X100 E1 F3000\n", $obj_id, $layer_id, 0.4 + 0.4*$layer_id + 0.1*$obj_id); # print same layer at distinct heights
         }
     }
@@ -92,7 +89,7 @@ $config->set('disable_fan_first_layers', 0);
     for my $layer_id (0 .. 1) {
         for my $obj_id (0 .. 1) {
             # use an elapsed time which is < the threshold even when summed twice
-            $buffer->gcodegen->set_elapsed_time($buffer->config->fan_below_layer_time/2 - 1);
+            $buffer->gcodegen->set_elapsed_time($buffer->gcodegen->config->fan_below_layer_time/2 - 1);
             $gcode .= $buffer->append("G1 X100 E1 F3000\n", $obj_id, $layer_id, 0.4 + 0.4*$layer_id + 0.1*$obj_id); # print same layer at distinct heights
         }
     }
@@ -134,4 +131,28 @@ $config->set('disable_fan_first_layers', 0);
     ok !$bridge_with_no_fan, 'bridge fan is turned on for all bridges';
 }
 
+{
+    my $config = Slic3r::Config->new_from_defaults;
+    $config->set('cooling', 1);
+    $config->set('fan_below_layer_time', 0);
+    $config->set('slowdown_below_layer_time', 10);
+    $config->set('min_print_speed', 0);
+    $config->set('start_gcode', '');
+    
+    my $print = Slic3r::Test::init_print('20mm_cube', config => $config);
+    my @layer_times = (0);  # in seconds
+    Slic3r::GCode::Reader->new->parse(my $gcode = Slic3r::Test::gcode($print), sub {
+        my ($self, $cmd, $args, $info) = @_;
+        
+        if ($cmd eq 'G1') {
+            if ($info->{dist_Z}) {
+                push @layer_times, 0;
+            }
+            $layer_times[-1] += abs($info->{dist_XY} || $info->{dist_E} || $info->{dist_Z} || 0) / ($args->{F} // $self->F) * 60;
+        }
+    });
+    my $all_below = !defined first { $_ > 0 && $_ < $config->slowdown_below_layer_time } @layer_times;
+    ok $all_below, 'slowdown_below_layer_time is honored';
+}
+
 __END__
diff --git a/xs/MANIFEST b/xs/MANIFEST
index db101d689..03e52ae50 100644
--- a/xs/MANIFEST
+++ b/xs/MANIFEST
@@ -52,6 +52,8 @@ src/libslic3r/Flow.cpp
 src/libslic3r/Flow.hpp
 src/libslic3r/GCode.cpp
 src/libslic3r/GCode.hpp
+src/libslic3r/GCode/CoolingBuffer.cpp
+src/libslic3r/GCode/CoolingBuffer.hpp
 src/libslic3r/GCodeSender.cpp
 src/libslic3r/GCodeSender.hpp
 src/libslic3r/GCodeWriter.cpp
diff --git a/xs/src/libslic3r/GCode/CoolingBuffer.cpp b/xs/src/libslic3r/GCode/CoolingBuffer.cpp
new file mode 100644
index 000000000..84df9cfd3
--- /dev/null
+++ b/xs/src/libslic3r/GCode/CoolingBuffer.cpp
@@ -0,0 +1,132 @@
+#include "CoolingBuffer.hpp"
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string/replace.hpp>
+#include <iostream>
+
+namespace Slic3r {
+
+std::string
+CoolingBuffer::append(const std::string &gcode, std::string obj_id, size_t layer_id, float print_z)
+{
+    std::string out;
+    if (this->_last_z.find(obj_id) != this->_last_z.end()) {
+        // A layer was finished, Z of the object's layer changed. Process the layer.
+        out = this->flush();
+    }
+    
+    this->_layer_id = layer_id;
+    this->_last_z[obj_id] = print_z;
+    this->_gcode += gcode;
+    // This is a very rough estimate of the print time, 
+    // not taking into account the acceleration curves generated by the printer firmware.
+    this->_elapsed_time += this->_gcodegen->elapsed_time;
+    this->_gcodegen->elapsed_time = 0;
+    
+    return out;
+}
+
+void
+apply_speed_factor(std::string &line, float speed_factor, float min_print_speed)
+{
+    // find pos of F
+    size_t pos = line.find_first_of('F');
+    size_t last_pos = line.find_first_of(' ', pos+1);
+    
+    // extract current speed
+    float speed;
+    {
+        std::istringstream iss(line.substr(pos+1, last_pos));
+        iss >> speed;
+    }
+    
+    // change speed
+    speed *= speed_factor;
+    speed = std::max(speed, min_print_speed);
+    
+    // replace speed in string
+    {
+        std::ostringstream oss;
+        oss << speed;
+        line.replace(pos+1, (last_pos-pos), oss.str());
+    }
+}
+
+std::string
+CoolingBuffer::flush()
+{
+    GCode &gg = *this->_gcodegen;
+    
+    std::string gcode   = this->_gcode;
+    float elapsed       = this->_elapsed_time;
+    this->_gcode        = "";
+    this->_elapsed_time = 0;
+    this->_last_z.clear(); // reset the whole table otherwise we would compute overlapping times
+    
+    int fan_speed = gg.config.fan_always_on ? gg.config.min_fan_speed.value : 0;
+    
+    float speed_factor = 1.0;
+    
+    if (gg.config.cooling) {
+        #ifdef SLIC3R_DEBUG
+        printf("Layer %zu estimated printing time: %f seconds\n", layer_id, elapsed);
+        #endif
+        
+        if (elapsed < (float)gg.config.slowdown_below_layer_time) {
+            // Layer time very short. Enable the fan to a full throttle and slow down the print
+            // (stretch the layer print time to slowdown_below_layer_time).
+            fan_speed = gg.config.max_fan_speed;
+            speed_factor = elapsed / (float)gg.config.slowdown_below_layer_time;
+        } else if (elapsed < (float)gg.config.fan_below_layer_time) {
+            // Layer time quite short. Enable the fan proportionally according to the current layer time.
+            fan_speed = gg.config.max_fan_speed
+                - (gg.config.max_fan_speed - gg.config.min_fan_speed)
+                * (elapsed - (float)gg.config.slowdown_below_layer_time)
+                / (gg.config.fan_below_layer_time - gg.config.slowdown_below_layer_time);
+        }
+        
+        #ifdef SLIC3R_DEBUG
+        printf("  fan = %d%%, speed = %f%%\n", fan_speed, speed_factor * 100);
+        #endif
+        
+        if (speed_factor < 1.0) {
+            // Adjust feed rate of G1 commands marked with an _EXTRUDE_SET_SPEED
+            // as long as they are not _WIPE moves (they cannot if they are _EXTRUDE_SET_SPEED)
+            // and they are not preceded directly by _BRIDGE_FAN_START (do not adjust bridging speed).
+            std::string new_gcode;
+            std::istringstream ss(gcode);
+            std::string line;
+            bool bridge_fan_start = false;
+            while (std::getline(ss, line)) {
+                if (boost::starts_with(line, "G1")
+                    && boost::contains(line, ";_EXTRUDE_SET_SPEED")
+                    && !boost::contains(line, ";_WIPE")
+                    && !bridge_fan_start) {
+                    apply_speed_factor(line, speed_factor, this->_min_print_speed);
+                    boost::replace_first(line, ";_EXTRUDE_SET_SPEED", "");
+                }
+                bridge_fan_start = boost::contains(line, ";_BRIDGE_FAN_START");
+                new_gcode += line + '\n';
+            }
+            gcode = new_gcode;
+        }
+    }
+    if (this->_layer_id < gg.config.disable_fan_first_layers)
+        fan_speed = 0;
+    
+    gcode = gg.writer.set_fan(fan_speed) + gcode;
+    
+    // bridge fan speed
+    if (!gg.config.cooling || gg.config.bridge_fan_speed == 0 || this->_layer_id < gg.config.disable_fan_first_layers) {
+        boost::replace_all(gcode, ";_BRIDGE_FAN_START", "");
+        boost::replace_all(gcode, ";_BRIDGE_FAN_END", "");
+    } else {
+        boost::replace_all(gcode, ";_BRIDGE_FAN_START", gg.writer.set_fan(gg.config.bridge_fan_speed, true));
+        boost::replace_all(gcode, ";_BRIDGE_FAN_END",   gg.writer.set_fan(fan_speed, true));
+    }
+    boost::replace_all(gcode, ";_WIPE", "");
+    boost::replace_all(gcode, ";_EXTRUDE_SET_SPEED", "");
+    
+    return gcode;
+}
+
+}
diff --git a/xs/src/libslic3r/GCode/CoolingBuffer.hpp b/xs/src/libslic3r/GCode/CoolingBuffer.hpp
new file mode 100644
index 000000000..01770a58d
--- /dev/null
+++ b/xs/src/libslic3r/GCode/CoolingBuffer.hpp
@@ -0,0 +1,39 @@
+#ifndef slic3r_CoolingBuffer_hpp_
+#define slic3r_CoolingBuffer_hpp_
+
+#include "libslic3r.h"
+#include "GCode.hpp"
+#include <map>
+#include <string>
+
+namespace Slic3r {
+
+/*
+A standalone G-code filter, to control cooling of the print.
+The G-code is processed per layer. Once a layer is collected, fan start / stop commands are edited
+and the print is modified to stretch over a minimum layer time.
+*/
+
+class CoolingBuffer {
+    public:
+    CoolingBuffer(GCode &gcodegen)
+        : _gcodegen(&gcodegen), _elapsed_time(0.), _layer_id(0)
+    {
+        this->_min_print_speed = this->_gcodegen->config.min_print_speed * 60;
+    };
+    std::string append(const std::string &gcode, std::string obj_id, size_t layer_id, float print_z);
+    std::string flush();
+    GCode* gcodegen() { return this->_gcodegen; };
+    
+    private:
+    GCode*                      _gcodegen;
+    std::string                 _gcode;
+    float                       _elapsed_time;
+    size_t                      _layer_id;
+    std::map<std::string,float> _last_z;
+    float                       _min_print_speed;
+};
+
+}
+
+#endif
diff --git a/xs/src/perlglue.cpp b/xs/src/perlglue.cpp
index 523d3fe06..552524eaa 100644
--- a/xs/src/perlglue.cpp
+++ b/xs/src/perlglue.cpp
@@ -15,6 +15,7 @@ REGISTER_CLASS(ExtrusionSimulator, "ExtrusionSimulator");
 REGISTER_CLASS(Filler, "Filler");
 REGISTER_CLASS(Flow, "Flow");
 REGISTER_CLASS(AvoidCrossingPerimeters, "GCode::AvoidCrossingPerimeters");
+REGISTER_CLASS(CoolingBuffer, "GCode::CoolingBuffer");
 REGISTER_CLASS(OozePrevention, "GCode::OozePrevention");
 REGISTER_CLASS(Wipe, "GCode::Wipe");
 REGISTER_CLASS(GCode, "GCode");
diff --git a/xs/xsp/GCode.xsp b/xs/xsp/GCode.xsp
index 507132dcf..78f1f9d1f 100644
--- a/xs/xsp/GCode.xsp
+++ b/xs/xsp/GCode.xsp
@@ -3,6 +3,7 @@
 %{
 #include <xsinit.h>
 #include "libslic3r/GCode.hpp"
+#include "libslic3r/GCode/CoolingBuffer.hpp"
 %}
 
 %name{Slic3r::GCode::AvoidCrossingPerimeters} class AvoidCrossingPerimeters {
@@ -70,6 +71,16 @@
         %code{% THIS->path = *value; %};
 };
 
+%name{Slic3r::GCode::CoolingBuffer} class CoolingBuffer {
+    CoolingBuffer(GCode* gcode)
+        %code{% RETVAL = new CoolingBuffer(*gcode); %};
+    ~CoolingBuffer();
+    Ref<GCode> gcodegen();
+    
+    std::string append(std::string gcode, std::string obj_id, size_t layer_id, float print_z);
+    std::string flush();
+};
+
 %name{Slic3r::GCode} class GCode {
     GCode();
     ~GCode();
diff --git a/xs/xsp/my.map b/xs/xsp/my.map
index c6308aca7..8f5f67d4e 100644
--- a/xs/xsp/my.map
+++ b/xs/xsp/my.map
@@ -197,6 +197,10 @@ OozePrevention*             O_OBJECT_SLIC3R
 Ref<OozePrevention>         O_OBJECT_SLIC3R_T
 Clone<OozePrevention>       O_OBJECT_SLIC3R_T
 
+CoolingBuffer*             O_OBJECT_SLIC3R
+Ref<CoolingBuffer>         O_OBJECT_SLIC3R_T
+Clone<CoolingBuffer>       O_OBJECT_SLIC3R_T
+
 GCode*                      O_OBJECT_SLIC3R
 Ref<GCode>                  O_OBJECT_SLIC3R_T
 Clone<GCode>                O_OBJECT_SLIC3R_T
diff --git a/xs/xsp/typemap.xspt b/xs/xsp/typemap.xspt
index e32271ac9..57109055a 100644
--- a/xs/xsp/typemap.xspt
+++ b/xs/xsp/typemap.xspt
@@ -164,6 +164,10 @@
 %typemap{Ref<OozePrevention>}{simple};
 %typemap{Clone<OozePrevention>}{simple};
 
+%typemap{CoolingBuffer*};
+%typemap{Ref<CoolingBuffer>}{simple};
+%typemap{Clone<CoolingBuffer>}{simple};
+
 %typemap{GCode*};
 %typemap{Ref<GCode>}{simple};
 %typemap{Clone<GCode>}{simple};