Windows 10 on an old PC | Is there any negative effect if I install Windows 10 in a very low processor laptop

while it is possible to install windows 10 on your older device, it is not recommended.

Minimum Specifications:

• Processor: 1 gigahertz (GHz) or faster.
• RAM: (1 GB: 32-bit) or (2 GB: 64-bit).
• Hard Disk: 16 GB.
• Microsoft Account.
• Internet Access.
• Graphics Card: Microsoft DirectX 9 Graphics Device with WDDM Driver.

Is there any negative effect if I install Windows 10 in a very low processor laptop ?

If your PC specifications are lower than minimum specification (as shown above), You should expect slowdown on the PC. If your PC is below the recommended memory, 1 GB on a 32-bit system and 2 GB on a 64-bit system, and you can expect to struggle. A test on Early Build of Windows 10 found that a 64-bit system with 512 MB of RAM (Random Access Memory)took more than 18 mins just to BOOT the system and was extremely slow to use comfortably.

It is better to choose lower end of windows OS (Operating System), if our PC has low processing power.