Harmony casting time doesn't fit UI casting bar

[scifo76]

VERY small issue, but noticable:

I use Duxa UI. When casting Harmony, it lands on a mob when there's about 1cm (half inch) left of the spell casting bar meter.
Either the spell casting time is too short in game, or the spell casting bar meter moves too slow. They don't sync.
Can a ranger test this to confirm? Maybe it's just a Duxa problem?