Why does Time Machine pause during backups on MacBook Pro?

I understand TM is taking a long time to finish a backup.

Review If Time Machine takes a long time to back up - Apple Support. Like most things about a Mac TM works best when it is ignored, but I understand it can be disconcerting or annoying when it repeatedly takes a long time to finish. One possible reason for that might be a backup drive that is functioning, but is nevertheless operating in a state of failure, so it would be instructive to obtain an additional TM backup drive and add it to TM. Besides, having one and only one backup drive does not comprise a robust backup strategy. TM will back up to as many drives as you wish to provide.

It is not necessary nor is it advisable to alter a Mac's sleep settings. Just ignore it.

Needless to say, if you are using any non-Apple "anti-virus", "cleaning", or "Internet security" products including "banking security", anything at all in that broad category of utterly useless garbage, don't. A lot of things won't work if you do.

Regrettably, some "ChatGPT" / automated AI-generated content has been posted to this Discussion. As is typical with such spew most of it is wrong and will only waste your time. However, following some of its suggestions will result in permanently corrupting your Time Machine backup, rendering it useless.

As such, that reply should be completely ignored.

In addition to good advice that you have already received: how full is your backup drive?

If the drive is getting full, Time Machine will need to delete the oldest backups to make room. Not only this usually slows down the process, but the drive too will perform worse as it gets fuller.

Thanks for that explanation. Of all the possible reasons for TM's slowness I think getting an additional backup drive will be the most expedient means of advancing troubleshooting. It can stall on writing to the backup device, reading the source drive, or both, or the trouble could lie elsewhere.

Time Machine troubleshooting can be time-consuming and tedious. If a new backup drive works well, it suggests the problems are isolated to the existing one, which we can address separately.