Boots of mobility and Sona

So this might just be my imagination, but i honestly feel like moblity boots don't give the level of movement speed they are suppose to to Sona. Played a lot of games recently where i'll have 50-60 movement speed above a team mate, and we will be running down mid them a little ahead of me at the start, and with them using no gap closers i still just barely seem to inch closer to them. To the point where even if they are only about 400 range ahead of me it still takes 80% of the mid lane run for me to get even with them (barring either of us hitting minions). Again i could be wrong but it seems very odd to me that a champion with 380-390 movement speed is keeping pace with me while i'm chugging along at around 450. It's seeming more and more like i have to outpace someone by 100+ movement speed to see any sizeable difference in our two speeds.

So i'd like to know if anyone else who plays Sona often is noticing the same kind of issue where Sona just seems to be super sluggish even with boots of mobility active. Or is this just me seeing an issue that isn't really there?