System freezing or v.slow when copying files to USB stick

Running on KDE desktop and I am having real trouble copying files to a USB stick using Dolphin.

The symptoms seem to get worse after an initial batch of files have been saved. I am working with batches of between a few hundred to several thousand files. I am working with one directory at a time. After a few seconds the system speed drops down to only several seconds per file. The total sizes of a batch is seldom more than a few GB. The stick also fails fully to eject.

I did a quick search and the problem was identified on several sites such as StackExchange but no clear solutions are apparent.

I am running with quite a well endowed system with a total of 24 cores and 64GiB of memory.
Pleas could somebody who knows about these matters please help and let me know what technical info you may require if needed.

Please ignore this post…All the hardware is getting in the way; usb etc.
I have an SD card reader in Workstation and am using that directly with SD Card. Speeds now acceptable and will complete 220GB+ write this evening.