Wow, that is a lot of upgrades; in my experience we only upgrade a single product at a time, fix that product's problems, then move on.
yes, it takes me slightly longer to get through an upgrade cycle, but I only have one upgrade to back-out if it is a disaster.
when performance is a problem I always look at the database, I do into the SQL Server Management studio, look at the activity monitor, and see
a) what queries are blocked
- 'Task State' is non-blanks
- sort by Wait Time descending
- check top processes
b) what the blocking process is
- Head Blocker ='1'
That will then give you some idea what process is wedging your SQL server and provide more help to SW tech support...
You have not told us what your actual servers are comprised of, but I am going to assume that you've done the usual thing and checked they have enough RAM and CPU cycles.