Fast is a relative term. Here is some perspective....

When I joined Yamaha burning your own wave ROM for a Synthesizer was not a user programmable thing. Back then, we’re talking late 1980’s, burning a Wave ROM was done at the Factory. An 8Mb Wave ROM (typical size back then) took about 15 hours. And it wasn’t like an oven where you just let it cook until it’s done.... every couple of hours you had to execute some tasks... so someone (actually a team of folks) would have to monitor the entire process. Yes, it was a nightmare. But I tell the story just to give you some perspective.

Today, It takes about 20 minutes for you to burn a gigabyte of data to a Flash Board, forgive me, if I have little sympathy for your pain, here. 8MB took 15 hours... your 20 minutes would translate to about 125 hours... so from my perspective.... burning a GB in 20 minutes sounds like an impossible dream. But it’s not your fault that in the old days it took forever... but just recognize that getting down under a half hour meant end users might be able to Do-it-yourself. Remember it was Factory only for many, many years.

The act of “burning a Wave ROM” (ROM being Read Only Memory) means you only need do it once. Then from this point on every time you power on your MOXF your 2048 custom Waveforms are ready to go, same as the Factory ROM Waveforms. The ROM remains until you manually DELETE it or you initialize the Board. You can keep the data on there permanently if you wish.

When I was using my Motif XS (2007-2010) which used volatile DIMM sticks ... I had approx. a 28 minutes load time every time I booted up.
When the Motif XF (‘F’ for Flash) came out, every time I powered on the XF I remembered the wait time I suffered with the DIMM sticks loading.

I make my living with my Synthesizers so it’s a daily thing, and on my own time I’m probably still playing with my synths so ...the XS got powered on virtually everyday.
Flash saved me over 10,000 minutes of *wait time* in the very first year.

What you choose to install to Flash should be specifically hand-picked by you. It literally extends the Factory Wave ROM with items you have decided you want to make a permanent part of your instrument.

A 20 minutes load time once, versus about a half hour of load time, each time you power up!!! Hmmm!

I estimate that in the years 2007, 2008, 2009, I spent in excess of 30,000 minutes drinking coffee waiting for my Motif XS to load up.
When the Motif XF introduced Flash, it saved me weeks (literally weeks) of sitting waiting for data to load. Waiting is time you don’t get back.

Take the 20 minutes, have a cup of coffee, and thank technology that you can select your own custom Waveforms, and at the end of the time it takes to install the data, you’ll never have to wait for it again. Now when you want to load up Voices that use those Waveforms, the files you load (without Waveform) will Load in seconds, not minutes. The maximum file load is going to 45 seconds from NOW ON! Why? Because all the custom Wave data is already in place. So you can load just the Voice parameters. The big Wave data is already in place.

The total size of all the Voice data (less the Audio Waveforms) is about 2KB. Say you want an Electric Piano Sound the parameters are about 2,000 bytes.
Meanwhile the Waveform data might be huge in comparison... the Chick Corea Rhodes is 400MB. That’s 400,000,000 bytes.
With the 400MB already in place, it takes approx 2 seconds to load a Chick Corea electric piano Voice.

You will need to contact your regional Yamaha office for specific help with PSR-S series Keyboards. This site is just for Synthesizer and Stage Pianos. They will be able to help you with the Arranger Keyboards and the content packs.