Before installing the patches from the out of box X1 version I had my system setup perfectly, low latency very responsive system.

Now after installing the c and then d patch (Producer X1) I have huge 1 second lag everywhere and my main MIDI keyboard doesn't work, the others still work, just my Yamaha KX8 motherkeyboard stopped working, it's still listed under MIDI devices and enabled but no midi is received anymore. My other midi gear works fine.

I fired up Ableton live and some standalone vst instruments to check if there was any problems there but it's still fine and everything works so the patch must have messed something up somewhere.

Is there any way to have Sonar rescan audio and midi devices like when you first install it?

Are you referring to the AUD.ini?
It is located in c:\Users\{yourUserName}\AppData\Roaming\Cakewalk\SONAR X1 Producer
You may want to rename it rather than deleting it, just in case.

Yeah I found that tip via Google, I've already tried renaming it but Sonar just started up without doing anything, it just silently recreated it without going though the rescan process.

btw scratch the MIDI keyboard error, for some reason all my midi track inputs got reset to my Saffire Pro 24 after the update instead of using any available input so that's why my KX8 didn't work anymore.

Still got the huge lag problem, I've been thought the preferences, tried switching from ASIO to mmc and back but that didn't help.

I'm thinking Sonar got confused about reported delay compensation somehow, it says 384ms and that's why I have this huge latency now. 

I'm hoping if I find a way to rescan the audio devices that would get cleared up.

AHA!

Fixed it.

I was trying everything I could think off, then I tried clicking on "Disable all FX" on the transport bar and the latency went away causing me to look at whatever fx plugins I had on the console.

The only one I had going was a Sonitus reverb on a bus which was strange as that shouldn't cause that much of a delay.

I removed it, re-enabled all effects, and reinserted it again, and the latency issue went away.

No idea what caused this but it's fixed now.

Now after installing the c and then d patch (Producer X1) I have huge 1 second lag everywhere and my main MIDI keyboard doesn't work

All you need to do is adjust your ASIO buffer or WDM sldier toget your latency low enough for what you wan to do. After updating to a new patch, you may need to set up your audio interface again.  Shoot for a roundtrip of under 10ms and one way under 5ms
 
Also, some plugins are for mixing, because they introduce latency. so make sure your not using one of those.
 
CJ

Yeah that was the strange thing, I got a reported overall latency of under 5ms and still got that +1 second lag, but as per my post above I got it fixed by removing the plugin and re-inserting it, must have been a temporary bug in plugin delay compensation.

I know about plugins such as convolution reverbs adding to overall latency.

It's all good now though.. time to make some music