Symfony2-Ajax响应缓慢

Whenever I make a simple Ajax POST request in Symfony, there seems to be a rather long waiting time before the response. Both in dev and prod environment.

I enabled XDebug to get a better insight. Here is what's going on on the server:

It seems to be Symfony's ClassLoader causing that long cycle. Page loads are similarly slow, generally over half a second.

I am running the application on localhost, on a Windows machine.

Is there any way I could reduce this execution time?