Huge frame spikes with low texture quality (specifically r.Streaming.PoolSize < 1000) after 4.14->17

We upgraded to 4.17 from 4.14 and started experiencing serious loss of frame rate on weapon switches. In game and in editor. I noticed the textures were streaming in slow and disabled r.TextureStreaming. Frame spikes immediately disappeared. I re-enabled it and started going through texture settings. Textures on Epic did not have this issue. I discovered that it was the r.Streaming.PoolSize that was affecting this when its value is below 1000, we were more likely to experience spikes. Making the minimum texture pool size 1000 doesn’t seem like a proper solution. Am I doing something wrong? This wasn’t an issue until we basically transitioned to the new texture streamer. I resaved all materials so they we would be updated for the new streamer using the command mentioned in the docs. If I disable texture streaming I don’t experience any spikes on weapon switching (though the other random spikes are still there).

Anyway, here are some screens.

Don’t understand this. r.HZBOcclusion = 0. Also if I’m indoors the culprit changes from hzb to lights. There’s just a huge spike when I pull the weapon out. HZB doesn’t even spike. Doesn’t make any sense to me.

CPU is just stalling, waiting for something? Uncompress Memory ZLib? Is loading the texture from the pak taking too long?

stat streaming

r.Streaming.UseNewMetrics 0 “fixes” my issues it would seem by reverting to the behavior before pre-4.15. Disappointing as I would like to be able to confidently take advantage of the touted performance gains.