Sorry should have mentioned that I have tried 3 synths, and they were all the same. 

I have also tried no speech, and got someone with site to watch as I used the computer and it was still lagging.

I turned the speech viewer tool on , and the sited person was able to see that most of the time that the computer would move the cursor, and then NVDA would output speech after a delay.

I went into windows settings and gave the following files  high performance on the Graphics performance settings.

nvda.exe

nvda_eoaProxy.exe

nvda_noUIAccess.exe

nvda_slave.exe

nvda_uiAccess.exe

If NVDA is not running the performance of the computer is not much different.  That is the computer seems to perform ok, however there is a delay from NVDA.

And here is another problem, which seems to me to be related.

Every so often NVDA will read the previous line and it will only read the line which I am on correctly once  I actually highlight that line.

There is no other way of getting it to read the line, it just will not read that text. Like never and I mean  never just will not read it.  It sees  the text in one line as another.  This is very hard to explain,

However, if you had one line which had the word cat, and another line which had the word dog,

Nvda would read the line which said cat, then you would arrow down to the line with the word dog, and nvda would say cat.

This problem  is intermittent. .

I just need it to go faster.