Mac OS lag when typing

Delete this file & restart...

~/Library/LaunchAgents/com.postgresapp.Postgres2LoginHelper.plist

~ tilde indicates hidden Home Library.

Apple hid the Users' Library folders...

Method 1:

1. From the Finder, select the Go menu at top of the screen, and choose Go to Folder.

In the window that opens, enter ~/Library/LaunchAgents, and click Go.

Safe Boot, (holding Shift key down at startup), does the problem occur in Safe Mode?

Safe mode attempts to repair Disks & clears lots of caches & loads safe Drivers, & prevents loading of 3rd party extensions, so if Safe Mode works try again in regular boot.

You can save us asking dozens of questions by submitting a report from this App for us to look at…

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Pastebin is a good place to paste the whole report if you capture the URL while there…

https://pastebin.com/

Whew, they've changed pastebin & made it harder, but after pasting in, click Create new paste button, then Embed button, then copy the URL...

<script src="https://pastebin.com/embed_js/KuvnghqA"></script>

The important part is...

https://pastebin.com/embed_js/KuvnghqA

Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

Uninstall AdGuard according to the developer's instructions. If you want to protect against adds use a Safari extension for that. They do not run in the background whenever you're booted up. As for adware and malware the download and run the free version of Malwarebytes occasionally. It was developed by a long time contributor to these forums and a highly respected member of the computer security community. 

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

IMPORTANT:

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

Also click and read the About info to further permit full disk access.

Then we can examine the report and see if we can determine what might be causing the problem.

Delete these 2 files & restart...

1. /Library/LaunchAgents/org.pqrs.karabiner.agent.karabiner_grabber.plist
2. /Library/LaunchAgents/org.pqrs.karabiner.agent.karabiner_observer.plist

I would get the free tool etrecheck and run it and post the result

possibly also install the free malware bytes program and run it to see if addware is causing it

I experience a similar issue with the Magic Keyboard, not sure if it's the keyboard, OS X or Bluetooth that causes it. Simply turning off the keyboard and turning it back on fixes the issue.

I wonder if you have a stuck install:

Top Processes Snapshot by CPU:

Process (count) CPU (Source - Location)

installd 57.16 % (Apple) <<<<-----

EtreCheckPro 18.10 % (Etresoft, Inc.)

WindowServer 11.42 % (Apple)

com.apple.WebKit.WebContent (8) 9.58 % (Apple)

Safari Technology Preview 7.22 % (Apple)

I don't see any of the usual suspects in the report.

Log into another vanilla admin user account, Set up users, guests, and groups on Mac,  and see if the problem persists. (This tells us if the problem is limited to your user account or is system wide).

Then, boot into Safe Mode (How to use safe mode on your Mac - Apple Support) by booting with the Shift key held down and check there to see if the problem persists.  Reboot normally and test again. (This tells us if there's any 3rd party software that might be contributing to the problem as Safe Mode prohibits all 3rd party software from running.)

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

What might have worked with earlier systems doesn't mean they will with Catalina which is more restrictive. It just makes sense to cull out the unnecessary software in order to give the most compatible environment for the system and apps to operate.