diff --git a/checkin_notes b/checkin_notes
index 9b646993eb..3fbac395e1 100755
--- a/checkin_notes
+++ b/checkin_notes
@@ -23783,3 +23783,22 @@ Rom    2 Feb 2005
     locale/
         <all localization files for the client are now here>
 
+Bruce  2 Feb 2005
+
+    - Made the caching of md5 info for source files a configuration option in 
+      config.xml.  Use the boolean tag <cache_md5_info> to enable it.
+      This prevents the work generation library from having to go back and
+      continuously regenerate the md5 sums of your input data files.  Note
+      that reading these from disk can be expensive if you have many such files
+      that are large and that you re-use. See check-in notes from 30/31 Dec 2004
+      for some details.
+
+    doc/
+        configuration.php
+    sched/
+        sched_config.C
+        sched_config.h
+    tools/
+        backend_lib.C
+
+
diff --git a/doc/configuration.php b/doc/configuration.php
index 0bb4479a23..c1b20adcf0 100644
--- a/doc/configuration.php
+++ b/doc/configuration.php
@@ -45,6 +45,7 @@ htmlspecialchars("
     [ <locality_scheduling_wait_period>  N   </locality_scheduling_wait_period> ]
     [ <min_core_client_version>          N   </min_core_client_version          ]
     [ <choose_download_url_by_timezone/>                                        ]
+    [ <cache_md5_info/>                                                         ]
 
     <!-- optional; defaults as indicated: -->
     <project_dir>  ../      </project_dir>  <!-- relative to location of 'start' -->
@@ -209,6 +210,13 @@ list_item("choose_download_url_by_timezone",
       file and executables must start with '/download/...' as in 
       'http://einstein.phys.uwm.edu/download/123/some_file_name'."
 );
+list_item("cache_md5_info",
+     "When creating work, keep a record (in files called foo.md5) of the
+      file length and md5 sum of data files and executables.  This can
+      greatly reduce the time needed to create work, if (1) these files
+      are re-used, and (2) there are many of these files, and (3) reading
+      the files from disk is time-consuming."
+);
 list_end();
 
 // THE INFORMATION BELOW NEEDS TO BE ORGANIZED AND PUT INTO TABLES OR SOME OTHER LESS CRAMPED FORM
diff --git a/sched/sched_config.C b/sched/sched_config.C
index f5aec5b5a8..772742e07c 100644
--- a/sched/sched_config.C
+++ b/sched/sched_config.C
@@ -91,6 +91,7 @@ int SCHED_CONFIG::parse(char* buf) {
     parse_int(buf, "<locality_scheduling_send_timeout>", locality_scheduling_send_timeout);
     parse_int(buf, "<min_core_client_version>", min_core_client_version);
     parse_bool(buf, "choose_download_url_by_timezone", choose_download_url_by_timezone);
+    parse_bool(buf, "cache_md5_info", cache_md5_info);
 
     if (match_tag(buf, "</config>")) {
         char hostname[256];
diff --git a/sched/sched_config.h b/sched/sched_config.h
index acf85b0b9e..f022e13f3e 100644
--- a/sched/sched_config.h
+++ b/sched/sched_config.h
@@ -60,6 +60,7 @@ public:
     int locality_scheduling_send_timeout;
     int min_core_client_version;
     bool choose_download_url_by_timezone;
+    bool cache_md5_info;
 
     int parse(char*);
     int parse_file(char* dir=".");
diff --git a/tools/backend_lib.C b/tools/backend_lib.C
index 2171629b9b..c543263999 100644
--- a/tools/backend_lib.C
+++ b/tools/backend_lib.C
@@ -62,7 +62,8 @@ int read_filename(const char* path, char* buf, int len) {
     return retval;
 }
 
-#ifdef BOINC_CACHE_MD5
+// see checkin notes Dec 30 2004
+//
 static bool got_md5_info(
     const char *path,
     char *md5data,
@@ -78,7 +79,7 @@ static bool got_md5_info(
     struct stat md5stat, filestat;
     bool retval=false;
     char endline='\0';
-    
+
     sprintf(md5name, "%s.md5", path);
     
     // get mod times for file
@@ -113,6 +114,8 @@ static bool got_md5_info(
     return retval;
 }
 
+// see checkin notes Dec 30 2004
+//
 static void write_md5_info(
     const char *path,
     const char *md5,
@@ -142,7 +145,6 @@ static void write_md5_info(
   
     return;
 }
-#endif // BOINC_CACHE_MD5
 
 
 // process WU template
@@ -193,20 +195,18 @@ static int process_wu_template(
                         );
                         boinc_copy(top_download_path,path);
                     }
-#ifdef BOINC_CACHE_MD5
-                    // see checkin notes Dec 30 2004
-                    if (!got_md5_info(path, md5, &nbytes)) {
-#endif
+
+                    if (!config.cache_md5_info || !got_md5_info(path, md5, &nbytes)) {
+
                         retval = md5_file(path, md5, nbytes);
                         if (retval) {
                             fprintf(stderr, "process_wu_template: md5_file %d\n", retval);
                             return retval;
                         }
-#ifdef BOINC_CACHE_MD5
-                        else
+                        else if (config.cache_md5_info) {
                             write_md5_info(path, md5, nbytes);
+                        }
                     }
-#endif
 
                     dir_hier_url(
                         infiles[file_number], config.download_url,