1) Given 8GB of non-upgradeable RAM, it will work better for you if your restart more often than 26 days:
System Software:
macOS Monterey 12.6.9 (21G726)
Time since boot: About 26 days ⚠️
A simple restart basically flushes RAM and does some housekeeping.
2) Yes, any after-market anti-virus and/or so-called "cleaning" apps will slow a Mac. They interfere with elegant self-maintenance and protection routines for which you paid Apple a lot of money to build into the macOS.
3) Your SSD is running at less than nominal speeds:
Performance:
System Load: 5.57 (1 min ago) 5.01 (5 min ago) 5.08 (15 min ago)
Nominal I/O usage: 10.83 MB/s
File system: 33.84 seconds
Write speed: 1224 MB/s ⚠️
Read speed: 1962 MB/s ⚠️
For that model Macbook Pro those should be over 2000 for Writes and up to 2700 for Reads. Completely removing the useless AVG dreck may see those improve. So might restarting.
4) You have two things using massive amounts of you CPU capacity:
Top Processes Snapshot by CPU:
Process (count) CPU (Source - Location)
installd 126.46 % (Apple) ⚠️
com.apple.WebKit.WebContent (6) 46.30 % (Apple) ⚠️
EtreCheckPro 18.26 % (Etresoft, Inc.)
WindowServer 13.38 % (Apple)
kernel_task 8.30 % (Apple)
The big one may be a stuck installer that a restart should clear. The Webkit issue affect Safari and is likely something AVG gave you to "enjoy."
5) Keep an eye on your storage free space. A 256GB SSD is tiny in the face today's OS and app needs and you may run into issues if the drive gets too full.
Bottom line is that AVG is currently masking any other issues that may exist. Completely remove it using the developers' instructions, restart the computer, and then see how your Macbook Pro runs with a 1000-pund weight removed from its back.