I guess they put 4 MHz resonator/crystals on them instead of 16 MHz? The workaround that comes to mind is to run off the internal oscillator at 8 MHz. I think that would be easier than making the Arduino IDE properly handle the 4 MHz clock since I don't know of an existing hardware package for that. Note that the internal oscillator is not as accurate and if it's way off this could cause problems with timing critical operations such as serial communication (and thus uploads).
It's pretty easy to change to the 8 MHz oscillator using MiniCore:
- Install MiniCore
- Connect an ISP Programmer to your target board. If you don't have a dedicated ISP programmer then you can use a spare Arduino board as an "Arduino as ISP" programmer.
- Tools > Board > ATmega328
- Tools > Variant > 328P / 328PA
- Tools > Clock > 8 MHz internal
- Tools > Programmer > select the appropriate programmer
- Tools > Burn Bootloader