I quote myself, "I had no issues with the old layout nor other sites". That means any other web page in the last ten years, even if they were slow to load due to size. My worst page to date is my TV listings web page which have about 1.3MB of html, 350kB of files and requires 52 "page downs" to get to the bottom. No problem once loaded, scrolls fine.
This page (.....bleepingcomputer.com/forums/t/484574/new-layout/) is not very long but still jerks - the html is 97kB, the 36 associated files are 1.28MB
ckeditor.js 368,670 (363,000 characters)
index_002.js 218,924 (219,000 characters)
index.js 193,731
all.js 178,930
index.css 79,354
cbgapi.loaded_0 76,358
fastbutton.html 38,662
editor.css 38,106
ga.js 37,398
ipb.js 26,033
plusone.js 22,611
prettify.js 13,632
lightbox.js 10,017
forum-logo.png 9,361
ips_config.js 5,091
post_top.png 3,076
default.js 2,966
av-3.jpg 2,774
loading.gif 2,767
ipb_print.css 2,715
default_large.png 2,589
skin.js 2,330
lang-sql.js 1,731
icon_share.png 1,201
feed.png 680
download.png 646
reddit.png 614
twitter.png 575
stumble.png 519
closelabel.gif 483
digg.png 431
print.png 409
icon_users.png 396
delicious.png 308
bullet_black.png 225
top.png 207
useropts_arrow.png 129
I realize that forums may need a fair bit of code but this seems somewhat excessive. It may be cached so that it does not need to be downloaded every page but the PC/browser is still handling a lot of kB. I suspect the problem is in the code rather than the amount of it.