On the project I’m working on, I noticed that, for whatever reason, it was now taking up to 3 minutes to start a web site running under GWT. That is, from hitting the “Debug” button and opening the web site in the browser, to seeing the web site actually up and running, was taking just shy of three minutes, with most of that time with the Spinning Beach Ball Of Death™.

I finally figured out what was happening. The first clue came from hitting ‘pause’ on the Daemon Thread labeled “Code server for myProject from Safari DMP…”, and noticing a lot of time being spent walking around inside the source kit for resources.

And noticing a lot of that time was spent in a bunch of .svn folders.

I think what was going on is that, for some reason or another, a lot of crud had accumulated in a number of random hidden folders associated with subversion. I don’t know if this is normal or abnormal behavior for Subversion; I just know there was a bunch of crap floating around there–and GWT was spending several minutes walking around the directory structure.

Blowing away the entire source kit and checking it all out fresh from Subversion reduced the startup time to less than 5 seconds. And it greatly improved the performance of the browser in the debugger as well: rollovers which were taking a while to get detected now are fast and responsive.

I suspect all the crud in my source directory was creating a lot of crap for the debugger to deal with, creating a substantial slowdown that got cleared right up.