[3.12] "Digital vibrance" Budget Impale Crit flicker champion - fast map farmer

As I said, the build is meant to be a budget build, that focuses on never running out of frenzy charges.
With that said, the easiest (and probably cheapest) way to get some extra damage would be to switch the amulet to a rare, with crit chance and multiplier rolls, and preferably with some "Adds # to # Physical Damage to Attacks" roll as well. If you anoint it and get Disemboweling to it, you can get about 15% extra damage.

If you have a starforge on hand, you can use it for clearing without much problem, especially if your flicker strike has +20% quality (that gives you a default 20% frenzy chance). With some cold snaps and blood rage you should be very safe with the charge generation. In this case you would have to switch to double strike or something similar for bosses.

You can also probably squeeze some extra resistances from other items to afford a darkray vectors boots for an extra frenzy charge. This is also an easy solution.

Another, even more expensive and probably not as safe variation would be to get some juiced up body armor with a crit roll from elder or hunter, but if you want endurance charges with it, you'll have to pay big for sure.

Other smaller optimizations would be to switch to diamond rings, or steel rings, getting some corrupts on items (like +1 frenzy to your gloves, or global phys damage to your rings). Getting a good Stygian vise with a good eye jewel also helps.

One last thing would be cluster jewels, but I haven't looked into it at all. However pretty much anything with Deep cuts should work pretty well).

First of all, you need to get the last lab done ASAP. Without Worthy foe, you don't have 100% accuracy which means you drop a lot of damage just by missing your targets (and some extra damage regardless from the notable).

You also don't have the impale nodes from the passive tree. By my calculations you have about 80% impale chance, which sounds good, but similarly to accuracy, you're dropping damage (about 10%) especially against bosses, just by not stacking impale on every hit. For more info, watch the video linked at the bottom of the OP.

Another "issue" is that you use belly of the beast. It's a nice armor, however it prioritizes life over damage, so you miss out on the increased onslaught effect. Daresso's would give you about 5% more damage, for 8% life less, but it also gives you extra armor (and since you don't have iron reflexes, evasion as well) with some attack dodge chance and endurance charges, so in the end, you probably lose less protection, than the damage you gain with a Daresso's (try to get one with 90%+ onslaught roll).

Finally, you should pick up the extra frenzy charge from the tree. That will also give you a lot of DPS boost.