If you edit too soon after posting, the forum flags it as possible SPAM, so that might explain it disappearing.
Certain file types/sizes are too much for the forums. I would double check those images. Also, they only allow so many images per post. I forgot and one of my posts is waiting for mod approval before it will be posted/revealed for others to read.
As for performance, I found if I have too many tabs open, or have not cleared my history/temp files in awhile, it slows/disrupts loading of various web-pages.
The wordpress… I only got when I tried to post links that the forums did not like… but that was several months ago. or it when I copy/paste part of an article to quote, and it has a hyperlink in it, the forums flag it as BAD.
Hope that helps.