Max amount of remotes i can combine

What is the maximum amount of remotes I can combine before it becomes extremely slow/unstable?

hello and welcome to the forum,

really, no simple answer to that question.

too many variables not related to rclone, such as
--- how you plan to use the combine.
--- the quality of internet connection.
--- the providers, each has its own issues. gdrive is very different from S3.
--- the mix of files from the remotes.
--- the specs of machine running rclone.
--- etc...

if you can provide more detail, we can better answer your question