IIS stops responding after recompile

I have my web app I'm developing under local IIS (so not not the visual studio embedded one). It works fine, I can go from page to page...

But if I then change the code and recompile, IIS stops responding properly for ~2 minutes. If I attach the debugger, then there's no executing code, but it just won't serve any pages.

If I stop the App Pool in IIS, then I get a 503 error instantly, but I then am prevented from restarting the App Pool for ~2 minutes with error: Cannot Start Application Pool / There was an error while performing this operation. / Details: / The service cannot accept control messages at this time. (Exception from HRESULT: 0x80070425)

As you can imagine, this is crippling my productivity. Only started happening a couple of days ago, I haven't made any changes to the code which I would have though would cause this problem... and it doesn't matter which page I touch and recompile anyway, it takes just as long to recover. Nothing in the event log.

Any clues as to where to start looking?

Add the following line to your web.config:

 <compilation optimizeCompilations="true" />

related article: http://www.dnnsoftware.com/community-blog/cid/135019/a-small-webconfig-setting-that-can-save-you-development-time