After some testing I found Xlibs.tcz startup script makes boot slow significantly.
Here's the command which makes TinyCore boot times UnAcceptable.
chown -R "$USER".staff /home/"$USER" 2>/dev/null
Well.. this depend on the files inside tc's home.
For me, it's my application source code. Especially TC kernel source code.
Which make boot times >1minute.
For the meantime, I will move my development directory outside tc's home.