I did check out your watchlist, and I'm afraid I have seen only the tiniest fraction of the dramas you've seen. So our tastes our different, but I get your request. Maybe one of these will spark your interest.
CDRAMAS
Even though I'm not seeing a lot of historicals on your watchlist, these period cdramas fit your requirements:
Under the Microscope - A math savant and his immature friend run up against landowner corruption in this Chinese period drama based on a real incident. Yes to the fast pace - it's 12 tight episodes. Romance in a subplot - doesn't get much screen time. This drama had me in suspense and made me curious about Chinese history.
Nirvana in Fire - takes a few episodes to get up to speed, but when it does it's like being strapped into a luge hurtling down the Whistler Sliding Centre track - you whip around a lot of plot twists and character machinations. Deservedly praised. There was a romance in the past, and the characters do feel nostalgic about it, and there's a reunited couple at one point, but romance is definitely minor in the grand scheme of Nirvana in Fire.
KDRAMAS
And here are two excellent kdramas that have suspense, humor, and irresistible forward motion. Each has an implied crush that doesn't go anywhere. Both are splendid and awesome in every way:
Angry Mom - A daughter's school life alarms her mom, who goes undercover as a student to protect her kid.
Good Manager - A gangland embezzler gets roped into helping some chaebol baddies cook their books. And they think they're going to pin it on him hahahahaha. Speaking of funny, this gave me the most laughs per minute of all the dramas I've ever seen.