Well this is a new one. 
Working on updating my backing tracks with Addictive Drums. What a difference good samples make!! It started with my new creations now sounding 2x better than my tracks using Session drummer.  
But I also wanted to fix a few Organ parts played on TTS-1. 
First recording pass always works fine. 
If I stop and re set I hit a note on the keyboard and it takes literally 30 seconds to play. 
I have all effects bypassed and my CPU is idle. MIDI buffers are over 1,000. 
Re starting Sonar does not fix the issue. 
I was going nuts and only deleting TTS-1 from the rack and replacing it solved the issue, but then the same behavior,, only one take allowed?? 
I then selected AD and it responded with no latency as well as other synths in the project. Only TTS-1 remained with this huge latency issue. 
Is TTS-1 no longer viable in modern Sonar land? 
I can stop using it but it is the anchor for over 100 of my backing tracks. 
I'm going to be re doing all of them to add AD as the drums so if TTS-1 has to go then this is going to be a lot more work. 

Just in case you for some reason work with it under X3... there was a bug which did that when the project has any tempo changes. That was only partially fixed, as last it was spotted that in case of loop recording, it still produce the delay.
 
The reason is not TTS-1 in particular but Sonar way to deal with DXi plug-ins.

I working with the March version of Platinum. I will be updating later this week when time allows. 
I will check for tempo changes being the issue. I don't often use them on cover songs.
But that said most all of my Midi files where made on an Atari and the Tempo was often inserted as an event at the 3rd beat of the sequence. All the PG changes etc had to be a few beats after the start of things would be missed. I think this is still the case with MIDI data. Never put anything at zero. 
So I always have Sonars default 100 BPM start until that event is hit. 
 
Mostly what I'm wondering is if the TTS-1 or DXi has become unstable in the new world.