Gibson shutdown Cakewalk operations in Nov 2017. BandLab purchased the Cakewalk IP from Gibson and released a new DAW called Cakewalk By BandLab based on the unreleased SONAR Platinum 2017-11. The upgrade
is free and supported
. All that is required is creating a BandLab
account (use the same email as your old Cakewalk Account), a 64bit version of Win7-10 (Win10 recommended) and an internet connection to download and activate the DAW using BandLab Assistant (BandLab's version of Cakewalk Command Center).
This forum will be archived soon. The new CbB forum is here
That said, the MIDI playback buffer is the usual suspect when dropping notes. I have never heard of anyone using a value in 5 figures and would be leery of such an extreme setting there or anywhere.
To my knowledge Session Drummer has never had problems with fast bounce.
Set the MIDI playback buffer to a sane value 500 to 750 should be enough though some like to use as much as 2500,
Bypass all effects by clicking the FX button in the Mix module (keyboard shortcut E). See if that helps. If it does there is problem with an effect. If there are other synths in the project temporarily archive the tracks to disconnect the synths so that just SD is playing.