Soulrend of the Spiral + Sands of Time

When I am casting Soulrend of the Spiral and creating a ton of projectiles it slowly lags the game/zone permanently until I am down to 10fps and the lights start flickering in the zone.

Tested with a friends computer (much more powerful than mine) and we get the same issue.

I can blast 100 Blazing Salvos everywhere and be fine, but Soulrend is a permanent decrease.