Hi @palatisa and welcome to the Knime Community.
Alternatively, you could do the unzip outside of Knime. You can check this thread:
Although the topic was about 7-Zip, similar approach can be done. You can try to unzip specific files via the command line. It will be much faster. It will take less than 20 sec to do ALL of them.
Once you extracted your 123.txt files, you can then go back to Knime and process the txt files.