Hey @StrangerBoy,
Both good questions!
Regarding song limit: there’s no hard limit on how many songs you can have in a single project, neither in Live nor in AbleSet. 300 songs with 3 or 4 tracks each is perfectly reasonable, and the fact that it runs fine confirms it.
What tends to affect responsiveness in large Sets is not the song count itself but the total number of clips and the zoom level in the Arrangement. Recent AbleSet betas include improvements to how communicates with Live, which helps a lot with big projects.
One rule of thumb worth mentioning: try to keep all your audio files in the same format and sample rate. Mixing sample rates forces Live to resample on the fly, and consistency generally keeps things predictable.
About editing tempo and whether it affects later songs, this depends entirely on how your tempo is defined, so it’s worth being precise here.
If you use warped tempo tracks set to Lead:
Live generates the tempo automation in the Main track automatically from those clips, and that automation is tied to the clips themselves. If you move or rearrange a leader clip, the resulting automation moves with it. So re-doing the tempo of one song will only affect the span that its own tempo track covers, and the songs before and after keep their own tempo definitions untouched.
Keep in mind that each song’s tempo track clip starts exactly at the song locator and ends exactly at the song’s end, with no gaps and no overlap between songs.
If you drive the tempo from manual automation in the Main track (Song Tempo parameter):
Here you do need to be careful. That envelope is independent from your clips, so edits can bleed past the end of a song if there are no breakpoints right at the song boundaries, so you have to be extra careful when you move those around.
Also, positions in Live are stored in bars and beats, so your locators and warped clips stay musically aligned when the tempo changes, but the actual clock time of everything after the edit shifts. That is normal and it’s exactly why keeping each song’s tempo self contained matters.
If all your tempo tracks are set to Lead and bounded to their own songs, you can re-do a song’s tempo without touching the rest. I’d still duplicate the project before a big pass.
That said, it’s worth finding the balance between the pool of songs you actually need available on a given night and what your machine handles comfortably. Rather than one giant session, you can split the repertoire across several sessions, or go with Multi-File Projects, where each song lives in its own ALS file and AbleSet builds the setlist across all of them, opening and closing sessions as you go. You get the whole repertoire in the setlist without ever having hundreds of unused songs loaded at once, and you can still call songs on the fly. Setup is quick: a folder with your ALS files, each one with a song locator at the start and a SONG END locator at the end, then point AbleSet at that folder from the menu bar settings.
Hope that helps!