The thing is he wasn't trying to kill naruto and sasuke
If he wanted to he could have finished them right away
Remember how fast haku was?
haku isn't that fast compared to current shinobi.
Once sasuke gets two tomoe sharingan, he could dodge haku.
That sasuke gets blitzed by weighted lee.
Then after training sasuke is as fast as weightless lee.
Then that sasuke gets speed-blitzed by KN0 Naruto.
And KN0 pre-timeskip naruto is more or less as fast as the standard jounin, who is well below konan.
And we also have base lee able to blitz a bloodlusted haku.
And part of the reason haku was so fast was because he surrounded naruto and sasuke with the ice mirrors. Konan can easily get out of that by dispersion, or simply won't fall into that.