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The speed at which a computer can execute a program depends upon the speed at which its CPU can process data. Therefore, when you compare laptops, you should look at processor speed which is usually expressed in megahertz.
Whereas faster processing capability is desirable, a faster processor doesn't directly translate into faster program execution. This is because processors are handling multiple tasks at the same time. Some applications can demand a lot of processor capability. You may be able to speed up processing by simply shutting down some applications while your program runs.
Another factor to consider is RAM size. RAM is where the computer stores the data it is currently working on, for example an Excel workbook. Data from the RAM can be retrieved much faster than from disk storage. The computer will automatically store data it can't keep in RAM in temporary locations on the disk. If you handle big workbooks with large programs RAM size is important.
Then, of course, there is the disk itself. SSDs are faster to access than HDDs, both for reading and writing.
On aggregate, don't get too excited about any of this. Buy a reputable brand of laptop with the best CPU you can afford (look at the name and its maker). Laptops are a hundred times faster today than they were five years ago. 10% more or less will not be noticable. But be prepared for laptops still being slower than desktops even today, even as they are preparing to be much faster again in the not so distant future.