SIMCITY 2013 RUNNING SLOW OR GLITCHING FIX
There is a lack of SimCity 2013 tips and fixes out there on the web these days. It seems most have decided not to play it anymore and fix it. I don't blame them because it's a very buggy game. In case there is one person out there playing this beside me and has an issue with a city suddenly running slowly I have found a fix. Clear the cache files out for the two locations. Just delete the two files.
C:\Program Files (x86)\Origin Games\SimCity\SimCityUserData\Cache.package and C:\Program Files (x86)\Origin Games\SimCity\SimCityUserData\GraphicsCache.package