diff --git a/src/engine/fileOps.cpp b/src/engine/fileOps.cpp
index 845ee98bd..7cdcd5c8e 100644
--- a/src/engine/fileOps.cpp
+++ b/src/engine/fileOps.cpp
@@ -2916,6 +2916,10 @@ bool DivEngine::loadFC(unsigned char* file, size_t len) {
     }
     ds.insLen=(int)ds.ins.size();
 
+    // optimize
+    ds.subsong[0]->optimizePatterns();
+    ds.subsong[0]->rearrangePatterns();
+
     if (active) quitDispatch();
     BUSY_BEGIN_SOFT;
     saveLock.lock();
diff --git a/src/engine/pattern.cpp b/src/engine/pattern.cpp
index 0a561376b..77255e084 100644
--- a/src/engine/pattern.cpp
+++ b/src/engine/pattern.cpp
@@ -18,6 +18,7 @@
  */
 
 #include "engine.h"
+#include "../ta-log.h"
 
 static DivPattern emptyPat;
 
@@ -40,6 +41,44 @@ DivPattern* DivChannelData::getPattern(int index, bool create) {
   return data[index];
 }
 
+std::vector<std::pair<int,int>> DivChannelData::optimize() {
+  std::vector<std::pair<int,int>> ret;
+  for (int i=0; i<256; i++) {
+    if (data[i]!=NULL) {
+      // compare
+      for (int j=0; j<256; j++) {
+        if (j==i) continue;
+        if (data[j]==NULL) continue;
+        if (memcmp(data[i]->data,data[j]->data,256*32*sizeof(short))==0) {
+          delete data[j];
+          data[j]=NULL;
+          logV("%d == %d",i,j);
+          ret.push_back(std::pair<int,int>(j,i));
+        }
+      }
+    }
+  }
+  return ret;
+}
+
+std::vector<std::pair<int,int>> DivChannelData::rearrange() {
+  std::vector<std::pair<int,int>> ret;
+  for (int i=0; i<256; i++) {
+    if (data[i]==NULL) {
+      for (int j=i; j<256; j++) {
+        if (data[j]!=NULL) {
+          data[i]=data[j];
+          data[j]=NULL;
+          logV("%d -> %d",j,i);
+          ret.push_back(std::pair<int,int>(j,i));
+          if (++i>=256) break;
+        }
+      }
+    }
+  }
+  return ret;
+}
+
 void DivChannelData::wipePatterns() {
   for (int i=0; i<256; i++) {
     if (data[i]!=NULL) {
@@ -54,81 +93,6 @@ void DivPattern::copyOn(DivPattern* dest) {
   memcpy(dest->data,data,sizeof(data));
 }
 
-SafeReader* DivPattern::compile(int len, int fxRows) {
-  SafeWriter w;
-  w.init();
-  short lastNote, lastOctave, lastInstr, lastVolume, lastEffect[8], lastEffectVal[8];
-  unsigned char rows=0;
-
-  lastNote=0;
-  lastOctave=0;
-  lastInstr=-1;
-  lastVolume=-1;
-  memset(lastEffect,-1,8*sizeof(short));
-  memset(lastEffectVal,-1,8*sizeof(short));
-
-  for (int i=0; i<len; i++) {
-    unsigned char mask=0;
-    if (data[i][0]!=-1) {
-      lastNote=data[i][0];
-      lastOctave=data[i][1];
-      mask|=128;
-    }
-    if (data[i][2]!=-1 && data[i][2]!=lastInstr) {
-      lastInstr=data[i][2];
-      mask|=32;
-    }
-    if (data[i][3]!=-1 && data[i][3]!=lastVolume) {
-      lastVolume=data[i][3];
-      mask|=64;
-    }
-    for (int j=0; j<fxRows; j++) {
-      if (data[i][4+(j<<1)]!=-1) {
-        lastEffect[j]=data[i][4+(j<<1)];
-        lastEffectVal[j]=data[i][5+(j<<1)];
-        mask=(mask&0xf8)|j;
-      }
-    }
-
-    if (!mask) {
-      rows++;
-      continue;
-    }
-
-    if (rows!=0) {
-      w.writeC(rows);
-    }
-    rows=1;
-
-    w.writeC(mask);
-    if (mask&128) {
-      if (lastNote==100) {
-        w.writeC(-128);
-      } else {
-        w.writeC(lastNote+(lastOctave*12));
-      }
-    }
-    if (mask&64) {
-      w.writeC(lastVolume);
-    }
-    if (mask&32) {
-      w.writeC(lastInstr);
-    }
-    for (int j=0; j<(mask&7); j++) {
-      w.writeC(lastEffect[j]);
-      if (lastEffectVal[j]==-1) {
-        w.writeC(0);
-      } else {
-        w.writeC(lastEffectVal[j]);
-      }
-    }
-  }
-  w.writeC(rows);
-  w.writeC(0);
-
-  return w.toReader();
-}
-
 DivChannelData::DivChannelData():
   effectCols(1) {
   memset(data,0,256*sizeof(void*));
diff --git a/src/engine/pattern.h b/src/engine/pattern.h
index 4d1070f3b..23a92441d 100644
--- a/src/engine/pattern.h
+++ b/src/engine/pattern.h
@@ -18,6 +18,7 @@
  */
 
 #include "safeReader.h"
+#include <vector>
 
 struct DivPattern {
   String name;
@@ -28,14 +29,6 @@ struct DivPattern {
    * @param dest the destination pattern.
    */
   void copyOn(DivPattern* dest);
-
-  /**
-   * don't use yet!
-   * @param len the pattern length
-   * @param fxRows number of effect ...columns
-   * @return a SafeReader.
-   */
-  SafeReader* compile(int len=256, int fxRows=1);
   DivPattern();
 };
 
@@ -59,6 +52,20 @@ struct DivChannelData {
    */
   DivPattern* getPattern(int index, bool create);
 
+  /**
+   * optimize pattern data.
+   * not thread-safe! use a mutex!
+   * @return a list of From -> To pairs
+   */
+  std::vector<std::pair<int,int>> optimize();
+
+  /**
+   * re-arrange NULLs.
+   * not thread-safe! use a mutex!
+   * @return a list of From -> To pairs
+   */
+  std::vector<std::pair<int,int>> rearrange();
+
   /**
    * destroy all patterns on this DivChannelData.
    */
diff --git a/src/engine/song.cpp b/src/engine/song.cpp
index 216a1bc4d..1adb33ebb 100644
--- a/src/engine/song.cpp
+++ b/src/engine/song.cpp
@@ -18,6 +18,7 @@
  */
 
 #include "song.h"
+#include "../ta-log.h"
 
 void DivSubSong::clearData() {
   for (int i=0; i<DIV_MAX_CHANS; i++) {
@@ -28,6 +29,34 @@ void DivSubSong::clearData() {
   ordersLen=1;
 }
 
+void DivSubSong::optimizePatterns() {
+  for (int i=0; i<DIV_MAX_CHANS; i++) {
+    logD("optimizing channel %d...",i);
+    std::vector<std::pair<int,int>> clearOuts=pat[i].optimize();
+    for (auto& j: clearOuts) {
+      for (int k=0; k<256; k++) {
+        if (orders.ord[i][k]==j.first) {
+          orders.ord[i][k]=j.second;
+        }
+      }
+    }
+  }
+}
+
+void DivSubSong::rearrangePatterns() {
+  for (int i=0; i<DIV_MAX_CHANS; i++) {
+    logD("re-arranging channel %d...",i);
+    std::vector<std::pair<int,int>> clearOuts=pat[i].rearrange();
+    for (auto& j: clearOuts) {
+      for (int k=0; k<256; k++) {
+        if (orders.ord[i][k]==j.first) {
+          orders.ord[i][k]=j.second;
+        }
+      }
+    }
+  }
+}
+
 void DivSong::clearSongData() {
   for (DivSubSong* i: subsong) {
     i->clearData();
diff --git a/src/engine/song.h b/src/engine/song.h
index 8b7eaa59f..de422a24a 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -138,6 +138,8 @@ struct DivSubSong {
   String chanShortName[DIV_MAX_CHANS];
 
   void clearData();
+  void optimizePatterns();
+  void rearrangePatterns();
 
   DivSubSong(): 
     hilightA(4),