I've noticed this in the past but I thought it stopped happening after a while (but it looks like I just got used to it).
And a few days ago I saw a huge improvement in both Heroes of the storm and Starbound when I just closed OBS (it wasn't recording)
Rig build is
intel 4770k (no overclock)
radeon r9 290
32GB RAM
60hz TV monitor
OBS and games are on SSD (recordings are saved on HDD but it's not relevant in this case since no recording)
1000 watt PSU
Asus Gamer pro motherboard
And a few days ago I saw a huge improvement in both Heroes of the storm and Starbound when I just closed OBS (it wasn't recording)
Rig build is
intel 4770k (no overclock)
radeon r9 290
32GB RAM
60hz TV monitor
OBS and games are on SSD (recordings are saved on HDD but it's not relevant in this case since no recording)
1000 watt PSU
Asus Gamer pro motherboard