I tested AmsBB with forum contains 213407 posts in 212848 threads (2,8 GB sqlite size) at local machine. Some note:
+ Overall performance is good, query for 1 connection is fast enough. DDos protection worked!
+ Slow when test with 50 concurrent connection: Page processing time: 2513.268 ms
+ Very slow with 100 concurrent connection: > 20s
I did not upload avatar for user, if I did the DB size will be much larger because AsmBB save image to DB.
Suggestion: save avatar to disk, much faster and less work for DB.
If you need some test, please tell me, I will try my best.