I am running some simulations in Python on my laptop, for my master degree project, and recently discovered that my desktop computer has almost the same performance of my laptop, when performing the same exact code. The problem is that my laptop has an i7 processor, while the desktop computer an i3. More specifically:
Laptop:  i7-5500U @2.40 GHz (64bit, dual core)
Desktop: i3-4150  @3.50 GHz (32bit, one core)
I am not an expert on computer science, neither I study it, and this is quite surprising to me. I know that the number of cores should not affect the performance, since python only uses one, but does it really all rely on clock frequency? And if yes, what are the advantages of having an i7 with such clock frequency? Is there some other data I am missing? What data one has to take under consideration to forecast computer's performance?
There are really too many factors in determining why your performance is like that. Consider:

Is your program memory-bound or calculation-bound?
Does your code really use multiple cores?
Is your program slowed down by disk access?
Are you using different language versions or performance settings?

There are really many factors like these; some of them are difficult to answer and impossible to guess.
You could try profiling this if important enough.
Comparing python performance from hardware specifics