Old nVidia GeForce GT 620M vs modern integrated Intel 620?

Forget about using your old laptop for any video editing whatsoever in Premiere: Not only is your system already six years old now, but that CPU has only two physical cores. You see, all U-series i7 CPUs up to and including the 7th Generation line have only two CPU cores (4 threads total). Only the 8th-generation line of U-series CPUs such as the i7-8650U have four physical CPU cores (8 total threads). And no GPU, not even a high-end one, can compensate for a CPU that's extremely weak by current standards.

As for the GT 620m, forget about it. Nvidia has stopped writing new drivers for it after March of this year, except for critical security-only patches. And even for what it's worth, it is actually as slow as, if not slower than, the newer integrated UHD Graphics 620 - and only if the memory bus width to the GT 620m is truly 128 bits (many 620m's have only a 64-bit memory bus).