[Phanx]

Tags:

return format('|cff%02x%02x%02x%s', r, g, 0, healthcurrent)

Very minor, but there's no need to spend CPU time turning that 0 into 00 over and over; just hardcode the 00:

return format('|cff%02x%02x00%s', r, g, healthcurrent)

You could even take that further and avoid that second format call entirely:

        local color
        if healthcurrent < healthmax then
                color = '|cffb40000'
        else
                color = '|cff00b400'
        end
        if healthcurrent >= 1000000 then
                healthcurrent = format('%.1fm', healthcurrent/1000000)
        elseif healthcurrent >= 1000 then
                healthcurrent = format('%.0fk', healthcurrent/1000)
        end
        return color .. healthcurrent

================================

powertype = select(2,UnitPowerType(u))

select is a complete waste of CPU time in 99.9999999999999999% of situations, including this one. Use a throwaway variable instead:

local powercurrent, powertype, pr, pg, pb, _
_, powertype = UnitPowerType(u)

...or just the less intuitive but equally effective method of overwriting the variable with itself:

powertype, powertype = UnitPowerType(u)

================================

                elseif powertype == 'FOCUS' then
                        pr, pg, pb = 255, 128, 65
                elseif powertype == 'ENERGY' then
                        pr, pg, pb = 255, 255, 0
                elseif powertype == 'RUNIC_POWER' then
                        pr, pg, pb = 0, 209, 255
                else
                        pr, pg, pb = 255, 0, 0
                end

In all these cases, those are the default colors for those power types, so rather than a list of "elseif" conditions and hardcoded values, just fetch the default colors:

                else
                        local c = PowerBarColor[powertype]
                        pr, pg, pb = c.r * 255, c*g * 255, c*b * 255
                end