If you just recently upgraded to windows 10 or updated your windows 10 (Especially if you just upgraded your Graphics Card Drivers) that's why you're having the issue.
The September update and any post update with Windows 10 causes massive lag for Everquest and even moreso Isboxer boxers. This is what I was told by numerous people, that Direct X was changed and/or being phased out depending on who I ask I have been told different things. Point is though, there were direct x changes with the September patch that haven't been addressed by Daybreak yet because they're too lazy and they probably don't want someone boxing 20 chars off one computer anyway.
Also I could be wrong but I think LAX and the isboxer people are being lazy too with updating the direct x files as well. I think this because taking Direct x files off an older comp and renaming the ones on the comps that dont work D3d9.dll.bak - switching the computers newer files from after the win 10 update with the files from BEFORE the win 10 update around in my compters/isboxer configuration actually improved my performance from 15fps to 25fps.
There are very very very few people I know that can use a windows 10 computer that's fully updated to box a large number of characters. (18+ chars I am saying)
Here is a thread I made around the time of that patch when a lot of us had issues:
https://www.redguides.com/community/threads/45868-Super-lag-since-patch
Some people were able to fix the issue but I know at least 2 boxers that hung up their boxing reins because it doesn't seem like Windows 10 is going to be very boxing friendly from here on out. I plan to purchase one or two really good windows 8 computers this year during Black Friday and install EQ on them. I won't upgrade them to 10 of course that way I will at least have two solid machines that can run EQ without this windows 10 bullshit
P.S - if you think it's the graphics card that's what I assumed my problem was too I use an Nvidia Gt 740 in my main computer and it runs better than my win 10 comp with a GTX 1050 in it. Because the 1050 was made AFTER the windows 10 update you can't install legacy drivers from BEFORE the windows 10 update. This pretty much made the 1050 video card obslete for Everquest. It only gives me 10 FPS better than my onboard graphics card. So 15 FPS instead of 5. All because of windows 10 and the stupid windows 10 update.