Have projects that worked fine before started to have problems, with all the same plugins?
 
It's all very well finding a plug that is causing problems, but if it worked with older
versions of Sonar, that's not good.

xwaveform
lol yes Gigs ;)   well I also do 3D art so I usually try and have a decent Graphics Card

Remember too that many graphics cards install their own "secret sauce" audio drivers which can totally screw up performance. I wrote a Friday's Tip of the Week about this. One company's drivers actually stopped the hard drive from streaming when it thought what was happening with the video was more important, so you had to set super-long latency to cover the times when the hard drive was stopped.
 

jpetersen
Have projects that worked fine before started to have problems, with all the same plugins?
 
It's all very well finding a plug that is causing problems, but if it worked with older
versions of Sonar, that's not good.

True, but there can be several reasons for that. Kingston upgraded to VST 3.6.5. Plug-ins written to conform to take advantage of 3.6.5 will work in Kingston but might not work in previous versions. Conversely, plug-ins that weren't totally compatible with the changes inherent in 3.6.5 might work fine in older versions of SONAR, but not in Kingston.
 
3rd-party plug-ins have been a moving target since the day Steinberg invented VST. Not all companies upgrade at the same time. This is one of the issues with monthly updates that is legit. SONAR can be on the cutting-edge of technology but that doesn't mean everyone else is. If SONAR waited a year to update to 3.6.5, most of the plug-in vendors would have caught up by then and allowed for a seamless transition to a new SONAR version. However the flip side is that during that year, those plug-ins that DID upgrade might not work with SONAR until the updated version of SONAR was released.
 

gustabo
What stands out to me is the nVidia card, that card can be a b*tch...
Lots of extra processes with that card...

I've been using my same Gigabyte fan less video card in three different computers over the past several years (XP, Win 7 was new machine and then Win 7 on a new mobo then Win 10 upgrade). It has thius far never failed me. And if it does. I have another spare machine (rarely used) that has the same card and I would just swap it and get a cheapo card for that machine.

Completely agree with the OP ... and those who say "choose the best for you" ... how could you know?  
 
I'm paused at Hopkinton, not because I know really anything about the others, just so I can concentrate on work, and work-arounds for the issues that concern me.   
 
Really, the older model of an update every so often when something significant was fixed or something significant was introduced is (for me) a better model.
 
For any CW developer reading this:  THE PRV CONTROLLER PANE IS REALLY REALLY REALLY REALLY REALLY TERRIBLE.
 

With the exception of one Windows 10 induced issue and one VERY slow SONAR update, the monthly updates have been pretty painless for me.  I like em.
 
I'm not trying to minimize the OP's issues...'just wanted to add a bit of balance.

 I read in another forum where users run the stock MS drivers in video cards instead of the AMD, Nvidia.

williamcopper
Completely agree with the OP ... and those who say "choose the best for you" ... how could you know?  
 
I'm paused at Hopkinton, not because I know really anything about the others, just so I can concentrate on work, and work-arounds for the issues that concern me.   
 
Really, the older model of an update every so often when something significant was fixed or something significant was introduced is (for me) a better model.
 
For any CW developer reading this:  THE PRV CONTROLLER PANE IS REALLY REALLY REALLY REALLY REALLY TERRIBLE.
 

You know by trying. If it is a problem just roll back. This is not rocket science. CW has been busy making this new system work for everybody.  

xwaveform
Monthly  updates = the most unproductive time I have ever experienced in 20 some odd years of using cakewalk. I spend more time lately trying to fix problems than I do getting anything done this is has got to stop.. I have a Brand new computer  i7 processor  16 megs of ram thing of upgrading to 32  baaa blaa blaa the computer has not changed the last 5 months the only constant change is a new update every month that never quite fixes anything. and then i spend countless hours in forums and trouble shooting only to get suckered in to next months update. No more im done i cant even begin so say how F*** frustrated I am with this. maybe time to find a new DAW ugggg

You are not alone in your frustration. So far I have only had major issues with 2 of my 6 updates so far, both of which have been fixed by an interim update or in the next update.   However, the Monthly approach is not my cup of tea either and I have been lobbying for Quarterly Updates with intermediate bug fixes for a while. (e.g. http://forum.cakewalk.com/FindPost/3308150 ).  Typically posts like ours bring out the same arguments from the same people so my purpose here is merely to lend my support for your post.
 
Keep in mind, however, that CW's marketing department probably controls this issue now and a monthly payment gives CW a steady income stream that only takes $10 - $15 out of the customer's account rather than $30 - $45 every three months.  As you can imagine it is easier to sell.  This has to do with the fact that many budget by the month.  It also manipulates the psychology of consumers by what is referred to as "reducing the pain of payment".
 
Cheers and good luck.
 
 

+1 to quarterly updates.
Cubase just released 8.5 and their forum is full of the same complaints about unfixed bugs even though they release only 3 or 4 updates per year. A couple of posts there even suggested a non-subscription subscription model would improve things.
I do not think in either CW's or SB's case the release model is the issue. I think it relates more to marketing philosophy and the need to attract as many new users as possible.