For details on what's coming in VistaDB Version 6 see:

What's Coming in VistaDB 6

We don't have a public date on that; we are presently working through the locking changes so we can release a beta with the new async API, multithreading, and locking.

We're expecting a beta to be available within the next 2-3 weeks.  It'll have several but not all of the performance enhancements planned for 6.0.  I'd recommend opening a support ticket (support@vistadb.com) with your specifics so we can give you guidance on how to make it faster in general with VistaDB and if the changes for 6.0 are likely to improve those scenarios.

The short answer is "when it's ready"; we are pursuing some specific performance gains and don't want to ship until we've integrated and tested sufficient enhancements to the low level of VistaDB to meet them.  I can say that presently we're hoping for June but we are still working to land a major top-to-bottom internal restructuring and until that passes our tests (and demonstrates performance) we don't have a date.

That said, this is on us - we announced to folks that had active maintenance as of January of this year we were on a maintenance holiday:  We would keep to our commitment that any Upgrade Assurance purchased as of 1/1/2018 would entitle you to VistaDB 6.  Once VistaDB 6 ships we'll be going through our records and extending maintenance for everyone based on the time from their normal expiration after 1/1/2019 through to the ship date.  This is why we haven't been sending out renewal notices this year.  If someone does renew on the website we have records of that too and you'll get the same credit - so it'll be that much longer until you need to renew again.  

This holiday only applies to Upgrade Assurance - premium support subscriptions and the like add features you've been able to take advantage of the whole time.