Since I updated to K2 2.7 i have a problem with the category list. With clean cache, everything runs great, but after some hours the category list-style is broken. Then the pictures are not available and tags,... looks like normal letters without any style. Then I need to clear the cache and everything looks good again. I never had this problem with K2 2.69. (I don't use the System-Cache, only the Browser-Cache)

Hello Fabian,

To be honest this seems more like a server side issue.
Can you try the following?

Enable Page or APC caching and disabling browser cache?

Ok Krikor,I will try...

Let me know how it went, performance wise as well.