diff --git a/manifest b/manifest
index 05732bb..9e70bda 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Make\sindexes\son\sCAST(...)\sexpressions\swork.
-D 2019-01-28T18:08:59.152
+C Fix\sa\sperformance\sregression\scaused\sby\sthe\sprevious\scommit.
+D 2019-01-28T18:58:54.614
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 9947eae873c07ae894d4c8633b76c0a0daca7b9fd54401096a77d1a6c7b74359
@@ -599,7 +599,7 @@
 F src/wal.c 3f4f653daf234fe713edbcbca3fec2350417d159d28801feabc702a22c4e213f
 F src/wal.h 606292549f5a7be50b6227bd685fa76e3a4affad71bb8ac5ce4cb5c79f6a176a
 F src/walker.c 7607f1a68130c028255d8d56094ea602fc402c79e1e35a46e6282849d90d5fe4
-F src/where.c c91b3dd6bb67abc7d4de879cf60e1fb57f5972045fc7b147f33537a1baecdfc0
+F src/where.c 8a207cb2ca6b99e1edb1e4bbff9b0504385a759cbf66180d1deb34d80ca4b799
 F src/whereInt.h 5f14db426ca46a83eabab1ae9aa6d4b8f27504ad35b64c290916289b1ddb2e88
 F src/wherecode.c 89d2ec668aec884dfa7ac500c6744e42ec0590fcd72fb740a8b48326a8412811
 F src/whereexpr.c 36b47f7261d6b6f1a72d774c113b74beddf6745aba1018e64b196e29db233442
@@ -1804,10 +1804,7 @@
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P a9faf9033910927c74553e66c474d84ed3386f263cef3eec299e25d8306f410d
-R 9a0f3b3b7b4bc83772f491da4476a586
-T *branch * index-on-cast
-T *sym-index-on-cast *
-T -sym-trunk *
-U dan
-Z cf3b41fd70871ac23ce42361c18f4249
+P 3ef711d98fb239cf24472f124e7b36b0dde33355de5a2c9a3a978bbdd042a735
+R 54fc32c05e999eaa7483855f7fbb2719
+U drh
+Z 51fba204c69fae1056723ec255ec3703
diff --git a/manifest.uuid b/manifest.uuid
index 5b02a6f..b78f5c2 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-3ef711d98fb239cf24472f124e7b36b0dde33355de5a2c9a3a978bbdd042a735
\ No newline at end of file
+c4db0ad12d4f3d2800d36404f391b325cdc4aa7f8dcea93b2d63a489d9095ad4
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 32f36d1..a09f762 100644
--- a/src/where.c
+++ b/src/where.c
@@ -311,6 +311,17 @@
 }
 
 /*
+** This is whereScanInit() for the case of an index on an expression.
+** It is factored out into a separate tail-recursion subroutine so that
+** the normal whereScanInit() routine, which is a high-runner, does not
+** need to push registers onto the stack as part of its prologue.
+*/
+static SQLITE_NOINLINE WhereTerm *whereScanInitIndexExpr(WhereScan *pScan){
+  pScan->idxaff = sqlite3ExprAffinity(pScan->pIdxExpr);
+  return whereScanNext(pScan);
+}
+
+/*
 ** Initialize a WHERE clause scanner object.  Return a pointer to the
 ** first match.  Return NULL if there are no matches.
 **
@@ -342,13 +353,19 @@
   pScan->pIdxExpr = 0;
   pScan->idxaff = 0;
   pScan->zCollName = 0;
+  pScan->opMask = opMask;
+  pScan->k = 0;
+  pScan->aiCur[0] = iCur;
+  pScan->nEquiv = 1;
+  pScan->iEquiv = 1;
   if( pIdx ){
     int j = iColumn;
     iColumn = pIdx->aiColumn[j];
     if( iColumn==XN_EXPR ){
       pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr;
       pScan->zCollName = pIdx->azColl[j];
-      pScan->idxaff = sqlite3ExprAffinity(pScan->pIdxExpr);
+      pScan->aiColumn[0] = XN_EXPR;
+      return whereScanInitIndexExpr(pScan);
     }else if( iColumn==pIdx->pTable->iPKey ){
       iColumn = XN_ROWID;
     }else if( iColumn>=0 ){
@@ -358,12 +375,7 @@
   }else if( iColumn==XN_EXPR ){
     return 0;
   }
-  pScan->opMask = opMask;
-  pScan->k = 0;
-  pScan->aiCur[0] = iCur;
   pScan->aiColumn[0] = iColumn;
-  pScan->nEquiv = 1;
-  pScan->iEquiv = 1;
   return whereScanNext(pScan);
 }