It appeared that lemmy-ui also causes random cpu spikes of load ca. 25.0 which made my small VPS unresponsive for a few minutes every few hours.
I have observed great performance improvement with mlmym but it lacks some basic functionality, so now I’m using Photon and with satisfactory result (btop):
True, 30M of footprint right now. I also decreased postgres hardware limitations as it was consuming a lot more memory than lemmy-ui. It was probably the culprit of those spikes but I’ll stay with Photon anyway :)