Hello everyone

I hope that I'm posting in the good section.
I recently started coding my own 2d game using SFML. It has quite simple requirments as I only want simple tile based 2d without any physics and collision detection.
One of the computer I'm using is a really basic laptop with 1Ghz processor, 2Go RAM (and about the GPU, I'm sure you can guess it's not a GTX980

) and with some non-moving sprites my game was running around 50fps. But has soon has I start moving the mouse it's lagging horribly, down to 1-5fps. I'm using a sprite for my cursos and each frame I use the sf::Mouse to get the position of the mouse and compare it to previous position to update the position of the mouse.
I have checked several times that there was no stupid overhead in the calculation of the cursor position and I still don't understand the issue.
So my questions are :
-from your experience with SFML, could you confirm that it's efficient enough to run on such a computer for basic stuff (so that you have a scale of power, it can run Super Meat Boy and Crypt of the Necrodancer with only small slowdowns when killing monsters) ? Has someone encountered such a thing before ?
-how are you managing the cursor position ? Is it different from my solution ? (i don't see anything else to do...)
And the second question is regarding using Godot engine instead of building my own stuff. I'm not highly experienced in programming (this work with SFML is partly a learning exercise for me) so I might not be able to create something good enough to be played. Thus I considered using Godot (side note : I tested a demo of 2d platformer running with godot and it was fluid on my computer, so the issue is not wit the hardware but rather SFML or my crappy code, probably the second

)
Has someone had experience with it and how was it ? What about ease of design / learning curve of the script / C++ API / performance / documentation ?
And if someone had experience with SFML and with Godot : what would you use if you had to choose between both now ?