Knime processing power blocking at every single step after finished flow

I had installed the 4.3 version and it was getting worse and worse in efficiency during two days.

I have installed 4.5 to see if it could improve. I have a two flows in the same workflow with just about 50 nodes of grouping, combining columns, filtering, pivoting, nothing special. If I reset the nodes the whole workflow runs in about a minute, not more.

Once finished if I just try to click on a node knime begins to consume 70% CPU and doesn’t open the node for configuration until 15-20 seconds have passed

Intel i7 series 8, 16GB ram, 6GB reserved for Knime memory.

Any ideas?

Gonzalo