Along with the severe lag, I've encountered a problem with the first quest in the thieves guild quest. After stealing Madesi's ring and planting it on Brand-Shei, Brynjolf talks to me and tells me to meet him in the Ragged Flagon inn, and just waits there at the stand forever

This has rendered me unable to join the thieves guild at all, and as a level 30 stealth-archer it's the most apt guild to join, and I have no previous save files I can revert back to.

This bug needs fixing badly, Bethesda! Hurry!