Using Apache 2.2 and PHP5.6 PHPBB3 is very slow to respond. Actually for some reason it takes so long to even register a log entry in access_log as in several seconds or a few minutes later it shows up in Apache. All other vhosts and Apache access stops working and freezes until the request to access PHPBB3 slowly completes.
It seems to randomly be slow if you stop using it whether for posting or reading the forums. I've migrated to different machines including........
The solution is simply "tidy"/Tidy-HTML. It will take your poorly formatted HTML code (and I mean files that span just a few lines that are unreadable) and fix it up.
Note the command below does everything in place. *Make sure you take a backup of all .html files*
It also seems to break html5 code/templates so beware.
tidy -im yourfile.html
An automated way in bash:........