problems with catalina

Boot into Safe Mode and try the apps from there. Any improvement? Reboot normally and test again.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing some system cache cleaning, volume verifying and directory repairing. 

Download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Add Text button to include the report in your reply. How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report

Before running Etrecheck assign Full Disk Access to Etrecheck so that it can get additional information from the Console and log files for the report:

Then we can examine the report and see if we can determine what's causing the problem..

I have a mid 2014 iMac with similar problems. Apps super slow to load, websites slow to load, getting messages in Safari telling me webpages are using to too much memory and I should close them, constant hanging.

I’ve have to force my iMac to shutdown twice today. If this continues, I’ll have to eat humble pie to all those windows users I laugh at from time to time.... please Apple, fix this, it’s the most unstable new operating system I have ever had! Safari and Mail both stalling.

I hope the update works, it took me 3 reboots just to get it to load properly!! even the software update box had overlaid text on it, so something serious wrong there. Downloading and installing (finally) now....

I have the same problem with Safari, but I am also unable to download Catalina, which I was hoping would fix the Safari problem. It started around the time of the Safari 13 update - Safari hangs, then mail hangs, then chrome hangs... and only rebooting the laptop (MacBook Pro 2016) allows me to do anything. If I don't use Safari, things are relatively stable.

Update didn’t fix the issues. Safari still hangs, not long after start-up, and refuses to open anything, then mail freezes too. This is my second iMac, and I’ve rebooted more times this week than the last 10 years combined across two machines! Apple, sort yourself out...

Same for me ... I had to restart my macbook three times today in order to download my mail.

Tried updating to Catalina again but it hung at 511 mb again with a timed out error.

Then hung my system so I had to rebook again into safe mode, and then restart.

Like Normski 100 above I have restarted by laptop more in the past 3 weeks than in a decade.

Really wish this would be resolved.

I have a 2018 iMac, same problem. Safari keeps hanging and only a restart fixes it since Catalina installation.