Hourglass Room in Trials of Sekhemas Horrible Performance

The Hourglass Room in the Trials of Sekhemas, where you have to survive while defeating enemies, has the lowest performance I've experienced in the whole Early Access of Path of Exile 2.
The frame drops are consistent, and reach unplayable levels as the game turns into a slide show while the enemies spawn in.

The Ultimatum has a similar "survive as enemies spawn" room, but doesn't suffer from the same performance issues.

Although my setup is extremely budget by today's standards, with an i7 4790k and a Radeon RX 570, this is the only area in the game I've experienced so far where the performance is actively detrimental to my experience.