Make me a fake loader
Powershell, 71 68 65 Bytes

Similar to https://codegolf.stackexchange.com/a/101357/59735

Saved 3 bytes by not being an idiot (left the ... on loading)

-3 thanks to VisualMelon

changed 750 -> 751 to make sure 750 is included.

0..100|%{cls;"loading $("|/-\"[$_%4]) $_ %";sleep -m(random 751)}


Explanation:

0..100|%{                                  #For range 0-100...
    cls                                    #Clear Display
    "loading $("|/-\"[$_%4]) $_ %"    #Display the current string
    sleep -m(random 750)                  #Sleep random ms up to 750
}


Updated gif