They are not slow at all
They are, it's just your PC is fast enough for you not to notice it.
Well how could I do that effect? My computer is not very good, just average for playing games. But if they really are "slow" and made to be accurate, then I want same accuracy too.
Your objects are either very small or moving super fast. You didn't specify your conditions. Also check your framerate.
Well they are moving very fast, I wouldn't say super fast. You can still easily see it on window when moving, but yeah it's small.. Also, I have capped framerate to 60, but I am planning to implement one good game loop with sfml. I have seen tutorial about it for java, it uses interpolation, and probably best game loop for both slow and fast machines.
PS. I'm currently working on my collision detection kit for C++ for my own SFML-based game, so if you post some details I may be able to help you (or I may not ).
Well. I am not having any project going on, I'm just practising SFML and more about c++. But if you have some accurate detection, I am listening.
Edit:
The prime optimization for collision detection between many entities is spatial partitioning. That should give you the needed keyword to research further on your own
Thank you. I will search about it.