To me, it seems GT2/U removes unused table entries and patterns upon export, but doesn't optimize much else.

Hi, I've heard some of your AHX work. Good stuff!

Keep in mind that no matter what you choose, SID tracking in general is more involved than using other trackers. Editing sounds requires the use of "tables", which are like lists of effect commands without much abstraction to guide you along. You can also set the length and speeds of individual channels independent of each other, which can become a bit hard to manage if you attempt it.

While I only know GTUltra, I find it quite comfortable, and its workflow is quite similar to Amiga MOD. (Hint: clicking on the labels above the tables will expand them into a more human-readable form). The only difference between GTUltra and GT2 is the interface. To me, it seems GT2/U removes unused table entries and patterns upon export, but doesn't optimize much else.

I believe SID Factory II is based on JCH's old music editor, which has its own slightly different workflow (especially regarding pattern management), but it does have some more capability than GT2 (such as full 12-bit cutoff control and arpeggio tables). It also has different music drivers you can select that each have a different amount of capability and resource usage, but overall its standard driver seems to use a bit more resources than GT2/U.

The latency is something that doesn't seem to be avoidable (at least on my PC), probably because SID emulation is quite involved.

The way to minimize the silence between notes can differ between editors, and it can depend on what kind of sound you want, as there are multiple ways to do it. In GT2/U, the least buggy way to do it is to set HR/Gate to either $01 or $82. This will result in only 1 frame of silence between notes. $01 will result in a "harder" attack, while $82 will result in a "softer/looser" attack. You can remove the silence altogether by setting the 1st Frame Wave to something other than 0/test, but that may result in glitches.

Good luck composing! I'm looking forward to hearing what you come up with on the SID.

It's quite common these days to have tunes with 6-8 KB or even more in music competitions. Especially from the top notch artists that deliver complex compositions and sound design.

Regarding editor / player: I found it very helpful to start with SID-Wizard on a real C64 and trying the PC emulation based trackers afterwards. It's way more easy to differ between user error and emulation limits this way. Even SID-Wizard in a recent VICE I think is a little more accurate than SF II or GT2 and its forks when it comes to the details. Because of this Cadaver made GoatTracker V2.xx Tweak Utility as an option to tweak your GT2 tunes on a real machine.

Anyone got any idea about how much the driver for GT2 and the drivers for SID Factory II differs when it comes to CPU utilization?

I doubt that I'm gonna do anything technically fancy just yet, so any songs that I produce shouldn't be in much need of tweaking.

Cool, hey Tommy! Probably around 30 years since we spoke last, you would remember me under a different handle back then. ;)

Stinsen (AKA "Mindshadow" back in those days :D)

Would really love to hear some SIDs from you! For the topic on hand I don't have much advice to give, but if you decide to go for GT I gathered a few of my song sources in a pack, could maybe be interesting:
Song Pack #1

One good choice would be Cheesecutter
CheeseCutter 2.9.0

Regardless of the editor used, SIDDump V1.08 is an excellent companion tool that (accurate enough for most purposes) shows what gets sent to SID.

I wouldn't recommend using CheeseCutter today. It's not being developed anymore, and it uses more CPU time than GT2 and SF2.

As you suggest yourself, I would choose GT2/GTUltra or SF2 if it has to be a cross-platform editor.

GT2 is the more popular option and uses less CPU time than SF2. It's also possible to do multispeed as well as tunes for more than one SID chip, neither of which SF2 currently supports. (Multispeed is being developed for SF2 but is not ready yet.)

Choosing between GT2 or SF2 is mostly a question of what kind of track system you like. If you want the track numbers to be edited in their own table, with sequences displayed one by one, go with GT2. If you like all sequences stacked on top of each other with track numbers in the left side of each sequence, go with SF2.

Couple of years ago I tested and made music with 12 different music editors.

Once I tried SF2, I felt I'm at home and it immediately clicked with me. This means, to my workflow and brain-capacity SF2 is the closest and best thing. Which, in your case might be different.

I'd suggest you to give GT2, SF2, CC and SID-Wizard a testrun, and not only a testrun but use them for a couple of weeks. Then you'll have a feel for one of them, that's gonna be your tool for C64 music. See, if you settle for one that is not right but people said it's the best... well, then you will feel frustration every time you start making music.

All of the above mentioned editors have great documentation (also, a SF2 tutorial from me is long due and it's also WIP). If you have any question, we surely can find you the best person to help let it be about GT2, SF2 or any of the music tools.