To speed up boot time, simply head to /etc/rc.d/rc.(1,3,5) and trim away anything you know you don't need. For example, you can remove things like Apache if you don't need a web server, squid if you don't need a proxy server, smbd if you don't need to share files with windows comps, and so on. Use man if you're confused by something.
To make a more efficient kernel:
1. Get the Linux 2.4.18 source. Save it to /usr/src.
2. Delete the /usr/src/linux directory. As strange as it sounds, this is a step I never skip.
3. Unpack the tarball you downloaded in step 1.
4. Download the
Preemptive Multitasking and
Lock Breaking patches to /usr/src.
5. Apply them the the kernel source.
6. Enter the /usr/src/linux directory and run "make menuconfig" if you're not in X, or "make xconfig" if you are.
7. Go through the options, checking every device you have and every feature you want. Make sure to select "Preemptible kernel" and "Lock breaking" in the CPU options menu. Those options enable the patches I told you to download.
8. time make dep modules modules-install bzImage
9. Go do something else, that's gonna take some time.
10. cp arch/i386/boot/bzImage /boot/kernel
11. Edit /etc/lilo.conf (if you're using lilo. I know nothing about grub) and add an entry for your new kernel, using the entry that looks like it's for your Linux system as a template.
12. Run /sbin/lilo
13. Reboot, and select the entry for your new kernel. Be amazed at how fast your system boots now.
14. Worship me as your god, and pray every night for more useful tips.
Just kidding about #14
I hope this has been helpful.