I am running an all LTSB shop and we have Instant Clones (IC) and Full Clones (FC) running Win10 LTSB. When we were standing up our first pools, we learned that running the optimization tool actually breaks the LTSB image. Start with a fresh copy of LTSB.
You need to also disable Windows Search because it will try to index everything, especially your Outlook mailboxes. With the non-persistent nature of Instant Clones it will do this every time a user logs in. This drags you down to the swamps. You should also disable Windows Updates and manually update your IC Gold Image (we do this once a month) then schedule a re-provisioning in View Administrator.
If you use a graphics card for shared accelerated graphics or dedicated slices (think Grid card) you can leave Search on as that dramatically reduces the load on your CPU. It worked for us, anyway.
I'll follow this thread and when I find more of our tweaks I'll drop back by to share them.