The forum software is indeed slow. A number of forums have changed the engines within last one or two years, and become slower and more difficult to use. The owners would probably say that they had to update in order to have a "supported" version. I'm sure that the main reason for these updates is to make the sites look like Twitter and Google Plus - "flat", and with strange terms like "content" and "follow" in place of common words like post, thread and subscription. For similar reasons flat "metro" design exists, and applications like CCleaner are compelled to change. Several people complained about MSFN's change of the board engine, and the reduced flexibility of formatting. (It is not possible to access a BBCode view in most new forums to compose long posts with multiple quote elements.) And despite that a major purpose of that board is to support Windows 98/2000 (never mind XP), they went forward and updated the forum anyway. Their site is a higher profile one... Some small forums still exist in 2016, running on vBulletin or older phpBB.
Proponents of flat, metro, material, xaml and social media style UI's will still claim that they are faster to render, when the opposite is obviously the case.
Disabling of JavaScript is still very useful on the modern web, and it can improve the experience. Most sites are indeed dynamic and require it, even if they could have been faster and more accessible if they were designed [without scripting]. Every once in a while I come over a site that does the following: after a few seconds or when I scroll down, the site spawns a frame of text that obstructs half of the screen asking me to "register to continue reading" or "sign up to a newsletter"; if I have blocked advertisements, they might redirect me to another page or dim all text, or it might interfere with scrolling, or prevent selecting, copying or right-clicking. In Opera, I can press F12 and disable JavaScript or referrer sending as soon as the page has loaded, and enable it back on when I'm done – without accessing Settings or downloading extensions.
Maybe Opera should have changed their brand name when they released an entirely different product. "Opium" is more appropriate.
I can still input a plain text reply in Opera, but any formatting exercises my patience.