How to get rid of lag when writing files in Ubuntu 19.04 to SSD?

Question

linux

Hello!
BACKGROUND
Have a working PC:
► CPU: AMD Athlon 870k (4.4 Ghz)
► GPU: MSI GTX 1050 Ti GAMING X 4G
► RAM: 8 Gb (1866 Mhz) Micron (Dual: 2x4 Gb)
► SSD: Samsung SSD 860 EVO 250GB ( Ubuntu)
► HDD: Seagate (2x500 GB)
► OS: Ubuntu 19.04
An example of the problem can be seen in the video: https://youtu.be/sfo-ZUYNgY8
A few days ago I moved from Ubuntu 18.04 to 19.04 (there was a clean installation, EXT4) .
Before that were 14.04, 16.04. I have been using Ubuntu for 5 years now and always on SSD.
Installed a new SSD, it is 3 months old.
PROBLEM
Literally on the very first day after 15 minutes of work every time when working with files, this is especially hard when downloading files through Chrome, I noticed the brakes. When you download any file, be it a 5 Kb image, the system hangs for 3-5 seconds, as if at the time of downloading in this version of Ubuntu some action takes place, which was not in the previous parts. Some kind of logging, indexing, scanning - I don't know, but something slows down.
And this is not a one-time thing, but every time you download files or upload them to the Internet, even when you delete them.
It also happens that after a few hours of work there are microplugging when typing (they are written with a slight delay). The GPU drivers are the latest from NVIDIA, the hardware is fine (since I reboot to Windows and everything is ok.). Previous versions of Ubuntu did not have this problem. I'm already thinking about going back to 18.04.
Search disabled.
File statistics are disabled.
Reading speed: 570 Mb/s.

QUESTION
Did you have a similar problem?
Perhaps you can tell me what is the reason and how to solve it?
Since I don’t understand how the text can be written with a delay on such hardware (now, by the way, it also happened 3 times).
PS. Answer, please, only if you have something to say on the case. Answers like "Stupid Ubuntu", "Stupid Linuxoid", etc. please keep it to yourself.