What other tehniques i can employ to make things better

That highly depends on your definition of 'better'. Considering your requirement of:

I can edit the files with text editor.

all typical methods to make access or store faster are disqualified.

There really isn't much Perl into this question. The fact that you are using a tied hash as part of the interface hardly matters for the answer - the tied hash is just syntactical sugar, and your question is really about the internal structure of the data file. And considering your requirements, you're most likely going to end up with flat files anyway - including full dumps. Regardless of your choice of implementation language.

You could of course read in all data at program start, and dump it on program termination, but that won't leave much if the required parallel access.

I'd use a SQL database server, where all the problems already have been solved for me. I'd be grateful that it takes away the temptation to modify the data in an editor - although it's not going to prevent me from doing it (most databases will allow you to dump the data of one or more tables to a text-editor edable file, and allow you to read in from such a file as well).

Abigail