When creating WinPE 2.0 boot images, make sure you run the PEImg /prep command against your boot.wim as it does make a significant difference in sze as shown in the table below:
| Bootable ISO file with WiinPE 2.0 | Size in MB |
| boot.wim prepped | 146 mb |
| boot.wim not prepped | 203 MB |
Considering this all is loaded into memory, you might want to make sure to reduce the size of the boot.wim to an absolute minimum.