How to set which compression to use for linux kernel image?

Hello,
I'm using vocore2, and I'm running OpenWrt in it, in flash Linux kernel image is stored in lzma compressed format, lzma takes a long time to decompress while booting so, how to change compression to lz4 compression?

Maybe TARGET_INITRAMFS_COMPRESSION_LZ4

Standard config searching tools work for the OpenWrt build system, including make menuconfig (use the / key)