There’s (at least) two problems in 3.7.0 with the application freezing under Windows (due to the graphics subsystem running out of resources.) One can be seen in using a loop with a large number of iterations, and the other involves working with annotations when there are a fair number of nodes and/or annotations also in the workflow.
The former has a fix that has been merged into the 3.7.1 release, and so can be found in the nightly builds.
The second has a fix that is waiting in PR at the moment; it seems likely that a merge will not happen until the new year. Later today (perhaps by 21h GMT,) i can make a drop-in patch jar available similar to what i discuss in this post - Workflow freeze & graphics problems with KNIME 3.7