util: improve textencoder encodeInto performance #1147

Job	Run time
Build slim tarball	1m 21s
aarch64-linux: with shared libraries	2m 3s
x86_64-linux: with shared libraries	2m 6s
x86_64-darwin: with shared libraries	2m 5s
aarch64-darwin: with shared libraries	2m 7s
	9m 42s

Provide feedback