So what is the cause of the slow-down?

Question

I take it data are not sent continuously.

Then, this means that sudden loss of performance is unexplained.

Clues:

• It usually happens when I open a new file in a new tab.
• Today, it happened even if I closed the old file to open a new one.
• Loss of performance = everything lags. Lagged drag and drop, takes noticeably longer to create a new item on the screen, etc.
• Current solution is: you have to restart the program to make it run smoothly.

I take my issue to be similar (if not identical) to this one: http://yed.yworks.com/support/qa/1278/performance-cpu-memory-usage?show=6603#c6603

Comments

Problems like these are very, very difficult to diagnose because we cannot reproduce these dramatic slow downs on our test machines.

One known cause for slow downs (that is not the result of a program error) is memory shortage. If you are working with large diagrams (several hundreds of nodes and edges or several large image nodes), this could be the case. The solution to this particular problem is assigning more memory to the yEd process as explained in How can I prevent 'Out of Memory' errors in yEd? (even if there are no errors).