OK, I think that turn based combat will always be slower than real time unless you select absolutely every auto pause option in rtwp.
Torment Tides of Numenera was slow as hell. But that was not only because it was turn based, but also how they did it.
FFX was one of the faster turn based games, even most boss fights were rather short if you knew what you are doing.
This was because:
- There were less units involved. You had up to 3 characters and up to 4 enemies. You could call a summon and it would replace all party members, not fight together with them.
- Most enemies could be killed with one hit. Even tougher enemies could only take a few hits. With the right tactics ( attacks with multiple hits, exploit elemental weakness ) you could kill bosses very fast. Often I did not kill all enemies as fast as possible so that every party member gets exp. ( You could switch party members during combat and only party members who did something during combat get exp)
- The game did not have combat movement or positioning.
Yesterday I fought the bosses of BoW and SSS in rtwp mode. In rtwp it took lots of hits to kill a boss. This was OK because all my chars were attacking at the same time I used summons who also attacked at the same time. I also used attacks that hit several enemies or that hit one enemy several times.
In a turn based game, you (and the enemy) need much less attacks to kill the target. In most good turn based games I know you can kill normal enemies with about 2-4 normal attacks. Special attacks or attacks that target their weakness can one shot them. If it takes more than 5 hits to kill something or there is a high miss chance, combat can take forever and become boring. A bad example is Wild Arms 3, where some bosses ( especially the optional ones) have tons of hit points and you just repeat attacks and healing forever.
Going from rtwp to turn based is not just about how to translate real time combat to turns and how to determine turn order.
You also have to change damage of attacks, HP of units, what some abilities do and the number of units.
Else it will become very slow and some stats or abilities will become useless or OP.
Adding turns is not enough, you have to balance everything almost from scatch.
One more advice: Do not add delay attacks.
These are attacks that push enemies back in turn order or make them skip their next turn.
They are OP in the Trails of cold Steel series (and maybe some other games) where you can prevent most enemies from acting at all.
Hard CC so that enemies cannot act on their turn is fine, but please no stuff that messes with the turn order itself.