Snapshot creating HUGE .tmp files. Max execution time issue?

Hi, I have for some time been finding snapshot creating loads of huge files which had been causing me to max-out my hosting storage limit which in turn has caused my host to suspend my account and take the site down. Fed up with this I was forced to turn Snapshot off and take backups manually (this sucked).

Last night around 1am I decided I'd give Snapshot another try. My hosting package was at 40% storage capacity of 7000MB. I setup a new snapshot schedule, set the destination to an FTP account and selected for it to run imediately. It ran without issue and created a 256MB ZIP file ("snapshot-5sta[...]" ). The snapshot status read "Uploading via FTP" or something similar. All seemed fine, so I went to sleep.

This morning I wake to find my site is down again and an email from my host saying my storage had been exceeded and was at 212%. After contacting them they have liffted the suspension for 24 hours to allow me to resolve the problem.

Of course, when I get into the Uploads/Snapshot directory, I find the problem is that Snapshot has created 10+ .tmp files, most over 1.5GB in size. I delete them all to reclaim the storage space.

The snapshot status now reads, "An unknown error occurred during the last upload attempt. Further attempts to upload will continue to be made."

It's not joking, I check the files again and in 30 minutes another 3 .tmp files have been created, it won't stop churning them out. I have had to disable Snapshot to stop it eating up all my web storage. What's going on here?

I can see Snapshot now has a requirements checker and it has flagged up a "Max execution time" warning. A time of 60 is detected and a minimum of 150 is requested. Is this the source of all my problems?

I know this might seem like the dumbest question, ever (clearly a minimum requirement is not being met) but the backup ZIP is being created so I guess my query is if the max execution time is likely to affect FTP uploading of the file specifically? Particually considering I have always had this issue, local backups always run fine, but FTP destinations have issues.

I've attached a screen grab showing the sucessfully created backup ZIP file and all the TMP files that Snapshot generated since.