MANY things could be at fault here:

1) triggers doing bad stuff

2) constraints doing bad stuff

3) blocking by other activity (I go with this by default for a 60K row tale without any other information)

I note you never actually said how long each update was taking nor how long you expect it to take. What is the hardware? Is it virtualized?

Assuming one update is running for multiple seconds at least you can use sp_whoisactive (awesome freebie from sqlblog.com) to determine what is happening during execution.