for some time I realized that to make entries or import text file or csv software is consuming a lot of CPU and slow
The file is quite small. Try to remove tick "Find duplicates" while importing data.
good day, .pdf database file is with 337 kb.txt file that care for example has 1 release and have size 1 kb
How large is you data base file? The import process is time and CPU consuming, that's correct.