According to surviving release logs and forum archives from sites like alt.binaries.warez and old-school FTP dumps, speed2.exe v1.2 is a —specifically a CPU/GPU throttling and performance modifier for older Windows systems (Windows 95, 98, ME, and early 2000s).
Popular tools like the ThirteenAG Widescreen Fix look for the v1.2 file header to inject code.
No discussion of speed2.exe v1.2 -hoodlum- is complete without addressing the elephant in the digital room: