"Play and/or record using RAM (useful for slow drives) so now audio is chached in memory not in my old drive
That may help in the short term. Computer memory is the sprinter. Blistering fast performance for a short time. Disk Drive is the long-haul performer. That's where you need to put the two-hour show you decided to make of crickets chirping.
Internally, Audacity works at really high quality and takes up a lot of room. Particularly on an older machise, you're going to run out of hardware memory in very short order -- worse, you're going to find out all about that ratty stick of memory that few programs use -- until now.
Even if you do use the hard drive for live capture, there are limitations to that, too. "I tried to record BBC-1 for nine hours and my computer crashed." How full, fragmented, or slow is your hard drive?
Live audio (or video) production retires many computers.
Koz
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