When some of your apps start playing up, try cleaning caches.

To clear your caches, including the system one, do this:

1. Quit all apps. Not just closing windows, but actually File > Quit all apps.
2. Open a Finder window and select Go > Go to Folder… ⇧⌘G menu item.
3. Copy and paste ~/Library/Caches and hit enter to open this normally invisible folder.
4. Move everything to trash. Don’t worry: caches aren’t documents, they get recreated when your system or an app needs them. But don’t try to empty the trash – some of the files might still be used.

Repeat the steps, but with /Library/Caches and /System/Library/Caches and then restart as soon as possible.

The first start will be slower but after that things should work better.

You can empty the trash now. It might take longer – it's a lot of small files.