Lag from going behind a box with shadow

[Former user]

https://images.discordapp.net/attachments/298512644808376323/333660257001799680/unknown.png?width=1208&height=755 When I go behind this box the game starts lagging so much that I want to go away from it asap. The lightning settings was on the lowest when I found this issue, but when I cranked the lightning settings on the highest... and I went back into there and the game ran smoother then.

[Matt D]

Re-made test scene, so this issue shouldn't feature anymore