Intonia will place demands on your computer in two categories: file usage, and processor usage.
The size of the temporary file, and any other files you can read or write with Intonia, is directly related to the length of the recording. For the default settings of 44,100 samples per second in stereo, about 10 megabytes of disk space is required for every minute of sound.
The Max Audio File Length option on the Audio Tab limits the maximum size of a recording. If the length of recorded sound threatens to exceed the limit, sounds are removed from the beginning of the tape to make room. This is analogous to splicing a tape in a loop.
If you uncheck Record in Stereo on the Audio Tab, that cuts in half the amount of disk space required.
If you cut the Sample Rate in half to 22,050 samples per second, that also cuts in half the amount of disk space required. You may notice a lowering of the quality of the sound recorded, but my guess is that the accuracy of pitch recognition will not be much affected.
To get the best use of Intonia, you should shut down any other computer processes that compete for processor usage. If another application seizes control, you will see the Intonia display freeze for a while, then catch up.
If you have a slow processor and it seems to have difficulty keeping up with recording sound in real time, your best bet is to double the Response on the Process Tab.
If you select a Pitch Method of "None", then all pitch processing is turned off, and the processor load is greatly reduced. But you won't be able to see the pitch analysis.