Have you ever started troubleshooting a performance issue with an application? Nothing else can be more frustrating that trying to resolve performance issues. Recently, I have been doing this on a SharePoint 2013 Server installation. Pages take a while, up to 5 to 6 seconds, to render the page properly. Sometimes, it was taking up to 20 seconds to render. I have been doing adjustments to the system as well as warming up the application pools. Much of this I will post on here in the future.
I listen to net/podcasts and thanks to Todd Klindt's Netcast, specifically Episode 152 - Splat Bang Click Hieroglyph, I found a possible answer for some of the performance issues I was seeing. He brought up Microsoft Support KB 952167 which is named "Certain folders may have to be excluded from antivirus scanning when you use file-level antivirus software in SharePoint". I had totally forgotten that AV scanning live systems like Exchange, SharePoint or SQL can make them crawl at times. It heavily affects PACS systems in healthcare, the Picture Archive and Communication System, for radiology imaging. I should have known better and went to the AV System Admin and asked to have these exceptions put in. Result was some improvement of the rendering. There's more to do but this did help.