I used LyX some years ago, creating a book of "haikus", it was a wonderful experience because of the final result - so amazing!

Now I'm running into a new idea and I'm struggling with a problem. I need to have a bunch of ASCII logfiles as the content of my "book" - I need to maintain the same formatting because it's ASCII graphics in there, and tables etc.
So any "chapter" in this book is a logfile - a plain text file.
I can't find a nice good way to import those text files into lyx

I tried joining all those text files into one single file to try a single big chapter with full text in it) but when I tried "import", everything gone to hell - CPU at 100% and LyX basically locked. (this on my GNU/Linux system, btw)
So I'm trying to find a solution - the best will be to have any of those files (some of them are about 250 - 300K in size) as simple chapters of this kind of book - mantaining the ASCII formatting as it is (and maybe changing the font in it, but that's another question)
Can someone help?
TY in advance
PS I'm using LyX version 2.2.2 under Devuan GNU/Linux (basically it's a Debian Stable)
asbesto