I didn't believe this when I first saw it, but it's true. Here is the execution time of `jstests/repl/mod_move.js` on a really fast Linux 64-bit box as of Sept 6 (rev def8f6fb859a04)

• Non-debug build: 18 seconds
• Debug build: 13 MINUTES

Example from MCI Sept 6 (rev 4b4fd431f5)

• http://mci.10gen.com/ui/task/mongodb_mongo_master_linux_32_debug_4b4fd431f5c28a4d138c113f9173abd5bb6526b3_13_09_05_14_06_07_replication_linux_32
  http://buildlogs.mongodb.org/mci_0.9_linux_32_debug/builds/96/test/replication_0/mod_move.js
  22.1881 minutes

Debug builds are expected to be slower, but this is seriously crazy slow, and that test failed because it was so slow.

How long has this been true? Most buildbot debug instances have been disabled so we've lost that data. Here is the one remaining one:

Buildbot Linux 32-bit debug

• Thu Sep 5 http://buildbot.10gen.cc/builders/Linux%2032-bit%20debug/builds/3259/steps/smokeRepl_smokeClone/logs/stdio
  9.4818 minutes
• Tue Jul 9 http://buildbot.10gen.cc/builders/Linux%2032-bit%20debug/builds/3062/steps/test_12/logs/stdio
  7.8618 minutes