Symfony2.5 slow Initialization time compared to Symfony2.4

Question

I just installed both Symfony2.4.4 and Symfony2.5.1 and set up a hello world page + some basic things I use (assetic js/css management etc). Configuration and setup for both projects are exactly the same.

I noticed that in app_dev the Symfony2.5.1 needs around 1100ms to generate the page, while Symfony2.4.4 only needs around 130ms to generate the same page. Both numbers come from the Symfony debug toolbar. When I take a look at the profiler's timeline I noticed Symfony2.5.1 uses around 900-1000ms for something called "Initialization time", while with 2.4.4 that only takes 50-60 ms.

Symfony2.5.1

Symfony2.4.4

Does anyone have an idea why it takes Symfony2.5.1 so much longer to initialize the project? I've checked the changelog for 2.5.x but haven't found anything so far. (https://github.com/symfony/symfony/blob/master/CHANGELOG-2.5.md)

Edit: Apparently the 2.5.1 rebuilds the entire dev cache on each page load, while the 2.4.4 does not. Not sure why.

Edit2: Noticed the chromehelper on my mac was running rogue (eating CPU), so I restarted the browser. Afterwards 2.5.1 doesn't rebuild dev cache anymore and load times are similar to 2.4.4. I don't get how it can be related though, how can a rogue browser influence the rebuilding of dev cache? FYI: The 2 projects are running on a virtualbox with centOS on that same mac.

Answer 1

The initialization time difference between both version was happening because Symfony2.5.1 was completely rebuilding its dev cache every time I loaded the page. I 'solved' it by killing off my mac/chrome browser which was running rogue.

After browser restart, 2.5.1 cache behaved the same as 2.4.4, with loading times around 130ms.

How a rogue browser can influence dev cache, I have no clue though.