Uf the problems are occurring when 32-bit plugins are present, it is quite likely that one or more of them are the culprit.
There were quite a few cases of this kind of issue. It used to happen to me, but I went through a process of firstly trying to use as many 64-bit plugins as possible, and then when any 32-bit ones were needed, I made sure that each one worked OK in 64-bit Sonar.
What I then did was to move those 32-bit plugins that worked OK to a brand new sub-folder within my existing 32-bit plugin folder, and ONLY allowed that new sub-folder to be added to the search path in my 64-bit Sonar install.
This eliminated crashes and freezes and all of that for me. Since then, I have literally just in the past week or so finished moving completely to 64-bit 3rd-party plugins, and have had nothing but smooth sailing.
You may consider picking up an alternative to the BitBridge routine that comes with Sonar. It is the software that 'bridges' between 32-bit plugins and 64-bit Sonar. Some people that have had prior issues with certain 32-bit plugins in 64-bit Sonar, using BitBridge, have reported those problems going away when they purchased JBridge, which is a 3rd-party bridging application.
Oh, if you have a 32-bit Sonar installed, it will still find any plugins that you move into that new sub-folder I refer to above, as Sonar automatically detects any sub-folders in the search path.
I hope any of the above both makes sense and is helpful,
Bob Bone