vm/vm_pageout.h defines the modes for the vm_compressor boot argument, which defaults to VM_PAGER_COMPRESSOR_WITH_SWAP (per vm/vm_compressor.c). You can disable compression by changing the vm_compressor_mode argument to 1 (VM_PAGER_DEFAULT). That is:
sudo nvram boot-args="vm_compressor=1"
Then reboot. You can verify the change was successful by running:
sysctl -a vm.compressor_mode