In many cases, an optical drive’s initialization routine can take an extended amount of time. In this amount of time, the drive won’t respond to the query of the motherboard/controller, causing an extended pause in some part[s] of the boot process.
You may be able to check some settings in the BIOS to see if you can speed up or skip the optical drive detection. In some cases, you can even disable the drive in the BIOS, but still be able to use it in Windows. [Just know that, to boot from the drive, you’ll have to re-enabled it in the BIOS].
Also, from my experience, the 3 noises you hear are normal. Drives tend to spin the spindle to check for the presence of a disc, and this particular Optiarc series causes the spindle to spin 3 times. Again, this is normal. This would also mark the end of the drive initialization routine, which is why the computer finishes booting after you hear it.
If you insert a disc into the optical drive, does it take any longer to get past the POST & begin loading the operating system than it currently does?