I've had my suspicions as to why people are reporting different behaviors with hordes, and different framerates despite having largely the same video card. I asked around with a lot of people reporting low frame rates and all of them reported running an i5 (which lets you set a maximum of 2 worker threads).
So I did some testing. For reference, I'm running this on an i7 3770 with 16gb of ram and a GTX 1070 with framerate limited to 60fps. Both runs are on the same settings, except for the number of worker threads allowed.
I set the game to run on a single worker thread and recorded a short clip of gameplay. Just wandering around in town my framerate was all over the place between 35-60 in the area just after you drop down, near the first tome. At around the 2:30 mark a Chaos Spawn engages, and at 3:00 a horde of skaven starts. Pay attention to them, they're thinly spread out and not a challenge at all.
I then exited and reset the game to run at 6 worker threads again. This clip shows the same map with the same settings, minus the worker threads. I wandered around the area near the first tome to get a feel for the frame rate there. It never strayed from a rock solid 60fps with no hiccups. I tried to get the horde to spawn in the same location, but I'd wandered too close to the elevator and had to go down to engage them. Pick it up at the four minute mark You can see the chaos swarm at the bottom is much denser, more populated, and overall a much greater threat. This despite the latest patch buffing the size of Skaven hordes.
The only difference between the easily ignorable "horde" of skaven and the chaos was the number of worker threads. I'm going to record a few more videos at both to double check, but its been consistant across what people on here and friends I have that play on low end machines are reporting: the game is easier to handle at lower worker thread counts, and the framerate troubles we've been having since 1.0.5 have been due to a CPU bottleneck.
Edit 1: First few minutes of Empire in Flames with 1 worker thread. Framerate around 35fps. Sorry for the quality on the first two videos, this one should be much clearer. May take a few minutes as it was still processing when I edited.
Edit 2: Empire in Flames but with 6 worker threads. Framerate wasn't as good as it was in the Cumberbun level, but the start overs lots of big sweeping vistas so I'm assuming thats what was dragging in down. Still stayed between 45-60 in non-horde times. The horde itself I managed to get in the same spot. This one was more responsive than the 1 core version, but not as big of a size difference as on the first set of examples.
© Post "Worker Threads and Their Impact on Framerate and Difficulty" for game Warhammer: Vermintide.
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