Your log says Windows 8 Business Edition build 9200. Must be the original version. Did you upgrade from 8 to 10? Did you revert/reinstall, maybe?
Maybe the load-time descreases if you've done one load. So you first load a singleplayer then join a multiplayer.
You have to deal with multiple bottlenecks. Suggest you lower all settings if possible. This game isn't that optimized and 'backwards compatible'; having stringent testing for new changes. So one day the unwritten assumption is that the amount of video mem is X.