UPS Random Drops

[completemuppit]

Running a smallish (IMO) factory in 0.15.12 (steam).

Factory will be chugging along at 60UPS and then drop down to 30 for no apparent reason. Occasionally it will pick back up to 60 but then usually drop back down. It's really random. Just played for 15mins at 60 but it's now dropped down to 30 for no apparent reason. Have attached screenshots of both speeds.

Running a Core i7-6700, 20Gb RAM, GTX980, SSD. None of the processor cores are anywhere near maxed out. Factorio is consuming <600Mb RAM and the entire system is only using 9Gb of RAM.

Any ideas where to start trying to troubleshoot?

60UPS

60UPS.png (10.71 MiB) Viewed 1807 times

30UPS

30UPS.png (15.02 MiB) Viewed 1807 times

[Smarty]

Could you please proivde the log?

[completemuppit]

Attached

factorio-current.log

(5.21 KiB) Downloaded 59 times

[Ubertwink]

Your UPS is still at 60, only FPS is at 30. Looks like a problem with vsync. Try disabling it.

[completemuppit]

vsync is disabled but in the second screenshot you'll see that the UPS is only 30.6. FPS is 30 because I'm playing on a monitor that only has a 30Hz refresh rate. I'm assuming the game (or video card) is not bothering to render any faster than that.

Regardless, current behaviour is that every time an autosave happens (currently every 2mins) the UPS drops down to 30. If I hit F5 to bring up the debug menu UPS immediately goes back to 60UPS. This will continue until the next Autosave when it drops back down.. This has just stopped happening. Now autosave does not affect UPS... gah!

Don't recall it doing this the other night and but the only setting I've changed is to disable Vsync. Really scratching my head.