[Kristo Kotkas]

Just an idea - if there is a certain plugin you see this on, try to disable all the rest of the plugins only and have that one enabled and see, if the sluggishness goes away. If it does, start adding back the plugins in half patches, not all together (remember what ones you enable back) and test each time for the sluggishness to re-appear. This way you can filter out if you have a plugin installed that causes this issue.