A) Fuzzy match repair

Project Settings - Language Pairs - All Language Pairs - Match Repair - Turn everything off

B) It has occurred to them, you just have to familiarize yourself with the software features. It's called LookAhead.

Options - Automation - Enable LookAhead

Disabling fuzzy match repair might also help a little with the lookup speed.

Thanks for these suggestions.

I was told by Jerzy in that other thread (community.sdl.com/.../sdl-2019-auto-substitution-of-numbers-not-working) that LookAhead is not a good idea (doesn't work well?) and should only be used on a less powerful machine. 

But you recommend it so I'll try it along with the other things.

Christopher Scully said:

But you recommend it so I'll try it along with the other things.

No she didn't. She just told you what the option was.

Lookahead is great when working interactively with machine translation or other remote resurces as it reduces the wait while Studio talks to the server.  If you're not doing this then turn it off.

Paul Filkin said:

Lookahead is great when working interactively with machine translation or other remote resurces as it reduces the wait while Studio talks to the server.  If you're not doing this then turn it off.

And, as with anything else, read the Help to understand what it does and to see if it's what you want/need.

https://docs.sdl.com/LiveContent/content/en-US/SDL%20Trados%20Studio%20Help-v4/GUID-A57EB808-DEDE-4CC7-94D3-10EDC09BB7F8

This part is particularly important:

https://docs.sdl.com/LiveContent/content/en-US/SDL%20Trados%20Studio%20Help-v4/GUID-A57EB808-DEDE-4CC7-94D3-10EDC09BB7F8#docid=GUID-91D2ED26-9870-421D-980B-CD1D708D7728&filename=GUID-91D2ED26-9870-421D-980B-CD1D708D7728.xml&query=&scope=&tid=&resource=&inner_id=&addHistory=true&toc=false&eventType=lcContent.loadDocGUID-91D2ED26-9870-421D-980B-CD1D708D7728

Paul Filkin said:

Lookahead is great when working interactively with machine translation or other remote resurces as it reduces the wait while Studio talks to the server.  If you're not doing this then turn it off.

And, as with anything else, read the Help to understand what it does and to see if it's what you want/need.

https://docs.sdl.com/LiveContent/content/en-US/SDL%20Trados%20Studio%20Help-v4/GUID-A57EB808-DEDE-4CC7-94D3-10EDC09BB7F8

This part is particularly important:

https://docs.sdl.com/LiveContent/content/en-US/SDL%20Trados%20Studio%20Help-v4/GUID-A57EB808-DEDE-4CC7-94D3-10EDC09BB7F8#docid=GUID-91D2ED26-9870-421D-980B-CD1D708D7728&filename=GUID-91D2ED26-9870-421D-980B-CD1D708D7728.xml&query=&scope=&tid=&resource=&inner_id=&addHistory=true&toc=false&eventType=lcContent.loadDocGUID-91D2ED26-9870-421D-980B-CD1D708D7728

Thanks Nora, I'll take a look at those links...