I've had no problems with the forum locking up. I greatly appreciate the lack of clutter and fast load times that the sigforum interface provides. Yes, it may require some scrolling to get around oversized photos on occasion, especially on mobile devices, but that's a small inconvenience compared to slow load times, "jumpy" interfaces, popups, and sidebars that you get on other sites.

To be clear on a few items based on some of the responses I got above.

I am running the most current MacOS Ventura 13.3 on a brand new Mac Mini and running the most current version of Safari 16.4. When the issue occurs it is not the computer that is locking up it is not Safari that is locking up, it is only SigForum that refuses to load. I can open any other site an it loads right up while SigForum is stopped at about 1/5 of the way loaded based on the status indicator in the address line. I can fix the problem by closing Safari and reopening it and then I can surf anywhere from one to a few pages on SigForum before it locks up again. I do NOT have to reboot the computer to fix the problem.

I noticed on Brave if I turn on the option to block cross-site trackers, it causes all sorts of issues here and on my scheduling app.

Hmm. No current problems regarding the forum with Brave (tracker block on) for me on a Windoze box or my laptop, or with either my Android phone and tablet when I'm using those. But a few months ago I remember encountering some weirdness with dropouts and incomplete post loading when using my Windows laptop. Tried clearing the cache: no relief. Even rebooted the laptop: no change. But I came back a few hours later, and everything was loading fine again.

 
I did find one DNS issue that could explain affecting only some users.
 
sigforum.com lists 4 name servers:
[helios]/Users/henry% dig sigforum.com ns

; <<>> DiG 9.10.6 <<>> sigforum.com ns
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 56683
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 4, ADDITIONAL: 0

;; QUESTION SECTION:
;sigforum.com. IN NS

;; ANSWER SECTION:
sigforum.com. 13841 IN NS ns3.evecommunity.net.
sigforum.com. 13841 IN NS ns4.evecommunity.net.
sigforum.com. 13841 IN NS ns1.evecommunity.net.
sigforum.com. 13841 IN NS ns2.evecommunity.net.

;; AUTHORITY SECTION:
sigforum.com. 13841 IN NS ns4.evecommunity.net.
sigforum.com. 13841 IN NS ns1.evecommunity.net.
sigforum.com. 13841 IN NS ns2.evecommunity.net.
sigforum.com. 13841 IN NS ns3.evecommunity.net.
 
ns3 and ns4 do not resolve to an IP address, and return NXDOMAIN when trying to resolve sigforum.com.
 
That does not explain why those having problems are able to load part of the web site, unless it is in their browser's cache. 

Thanks, henryaz for pointing this out. I contacted our excellent host (who is also the author of out platform's software):

Thanks for pointing this out. We did some DNS consolidation / migrations last month and I must have missed transferring the ns3 and ns4.evecommunity.net A records. I apologize for that. I have added them so hopefully if anyone had cached some bad DNS responses that were causing resolution issues they will clear up once their browser / device / computer / network checks again.

Another thing it could be is that we do maintenance updates usually sometime during the first week of every month. These are generally very minor package updates to keep the server operating system current but also consist of service restarts or a reboot, to make sure everything is still running properly, which causes a minute or two of downtime before everything is up and running again. If someone tries to access your community during one of these periods they will likely get some kind of timeout message but it should recover within a minute or two.

For any Windows user who are experiencing these issues, you can flush your DNS resolver cache immediately by opening a command line and entering the command ipconfig /flushdns and hitting Enter.

Again, thanks to henryaz, and thanks to our host Crowdstack who keeps this forum up and running 99.9999999% of the time, and with the fastest response times of any discussion forum you're likely to visit. It's the truth. Under normal circumstances, pages load like lightning. We couldn't ask for a better host.

 
macOS users will open the Terminal app, and enter these two commands to flush the DNS cache:
 

/usr/bin/sudo /usr/bin/dscacheutil -flushcache
 
/usr/bin/sudo /usr/bin/killall -HUP mDNSResponder

 
That is for newer versions of the OS. Older versions used a different command, and I do not recall where the change was made.