Forum appears to be slow

Few of my memebers complain how the forum is very slow, they can log in and get to their posts but once they try to begin to type it slows down. It takes like 10 minutes to post a small message then when they hit post it erases. Personally I don't have such problem, the forum works fine for me and rest of my members. Anyone can help?

My forum is: http://thetudors.forumsr.com/forum

Are the members with this issue from the same area, using the same Internet provider, browsers, etc.?

No they are not from the same area, or using the same Internet provider, for browsers one of them tried all of them, and it didn't help, the others use Firefox.

Please ask your members to do the following:

 Trouble shooting tips:
Scan your computer for problems,
Clear browsers of cookies and cache,
Reset internet router's,/ wifi / Modems,
Reset your computer,
Make sure your internet is running right by calling the ISP, (Internet service provider)
Plugging the computer to an Ethernet cable to see if the speed is better,
make sure all browsers are up to date,
Turn off any browser plugin's,

All of the following steps are a step to take as they all can slow forums down on their end.
Also some places have slower internet than others so making sure you have less codes and big moving pictures and images can help them lot's as slow internet speeds take longer to show them up.

 My Tests:
I open up your site and run a speed test
Results:
Load speed - 0.9 seconds "That's less that 1 second"
Navigating speed - 0.6 seconds "That's less that 1 second"
Items loading - some items are not loading see screen shot

Screen shot:

fixing this will help you speed slow internet speed users lot's.
in some posts your members have a lot of big moving images in the signature's asking your members to limit them sort of items will also help

also I have seen that them items come from a host "media.tumblr.com" This host is running a little slow when following the link at the bottom left of your site
members name with this is Amelia Cleves and Jane Seymour

making this small change will help you lots.

Thank you so much for your help Ape. I will let them know about your suggestions and fix the one you told me about. I don't know why those images are not loading I like changed them a few days ago.