Here's a thorough guide to get through TTF more quickly when fighting Vol Opt in phase one, especially in Ultimate mode. This special technique is called the Gizonde glitch.
Equip a V801 first, and use the Gizonde glitch to stun lock this boss when it tries to move through the screens. The more ATP your character has, the less times you need to cast Gizonde to beat Vol Opt in the first phase. This glitch is dependent on the character's ATP/DFP damage calculation rather than the character's MST/ETH damage calculation to beat this first phase of the boss in a short span of time, and it is advised to use the quick menu with Gizonde listed on top of the list of techniques. Let me remind you how to sort a technique in the quick menu in case you forgot.
To swap techniques on the list of techniques after opening up the quick menu for techniques; press tab to grab the desired technique first, scroll up or down to where you want the desired technique to appear on the list of techniques, and press tab again on the technique. If you rather press F3 to trigger Gizonde over the quick menu, then that may not work, but I haven't checked either. Ugh, moving on.
Before going into strategies, it is important to mention that only one player should attempt to perform the glitch as having multiple players attempting to do this will cause the first person to be unable to keep the boss locked in place meaning that Vol Opt will eventually attack everybody that's vulnerable with its totems. Please don't interrupt the first person that initiates the Gizonde trick. Now let's talk about some strategies on what equipment to use in order to take advantage of this glitch.
Strategies To Use The Gizonde Glitch
For HUmars and RAmars, either remove the weapon or equip a fist weapon for more ATP, preferably Sacred Duster, since their highest level of techs are not fast enough to keep Vol Opt stunned when either character does not use their fists to cast Gizonde. You can use an Excalibur or Galatine as well to perform the glitch too since it will be explained below for other characters, but the trick in this case is that Vol Opt must stop dashing to glare first. Due to how easy it is to mess this up, I usually recommend punching it to death with Gizonde.
For HUnewearl, RAmarl, FOmar, FOmarl, and FOnewm; equip Excalibur to stun lock Vol Opt with Gizonde. These 5 characters, except for FOnewm, can equip Galatine to beat Vol Opt faster at the right time of the day since it will have more ATP than Excalibur at beat times between 500-624.
For FOnewearl, her best strategy is to equip Crimson Coat and Red Saber since she cannot equip both Excalibur and Galatine; also, consider using these two items (Crimson Coat and Red Saber) if you don't have other high ATP weapons since they are the most affordable option with the most bang for your PD!
If you prefer to use other weapons because you don't have the means to use the recommended gear, adding some %'s in Machine on your most powerful weapon for the task can help, although it's best to find them with a lot of %'s in Machine beforehand. As a bonus, consider using frames and barriers that add a little more ATP now that I linked those here too.
Here some (1, 2, & 3) videos of what it looks like to perform the glitch well. All right, the first link in that short list made me laugh, but it's a reminder that interrupting someone can be bothersome to some players. It can be even dangerous if the party has a couple of weaker players around, so be sure that everyone knows who is responsible for performing the Gizonde glitch before entering the warp to fight Vol Opt.
Backup Plan - Strategies That Don't Use The Gizonde Glitch
If no one in the party can use this glitch then these are some strategies to still stun lock Vol Opt.
The Casts do have their strategy to stun lock Vol Opt in phase one without Gizonde since they can't use Gizonde, and it's actually a rifle instead of a handgun or launcher too. Equip Drill Launcher to stun lock this boss with a NS combo, and repeat that combo if some screens do break. Also this weapon can hit multiple screens because its special attack is penetration which hits Vol Opt harder than the normal attack. Be wary that breaking screens is not the goal; instead, the goal again is to keep Vol Opt stunned until all of its hitpoints are gone. Here's a funny video showing how it is done with some interruptions from others.
Another method to stun lock Vol Opt is to perform NNN combos with a Spread Needle, ES Needle, or any handgun if necessary, and be prepared to break a few sets of screens at the perimeter of the room while Vol Opt's digitally dashing through them. It is possible to keep the screens from breaking by performing NSN combos, but that may not keep Vol Opt stunned for long after initially practicing this combo; as mentioned elsewhere above, the trick is to have Vol Opt stop dashing to glare first before engaging in this special technique.
The Last Resort
If the party fails to stop it, hope that someone breaks all six red totems before someone gets hurt or worse - killed or maimed by a status ailment like freeze or shock.