Help - how to code the right way to avoid big load in MQL4?

Hi,
i learned coding since some years ago, but i think my coding ability is not improve much ... ... still learning thought ...
some times i found that my indicators are very slow, and some of them make my MT4 freeze ...
To avoid big load, i try to do these (please see example source code below) :

*) limit the bars to calculate, not using the whole Bars() => i use lookbackcandles here ...
*) trying to calculate it only once at a bar => using newbar check
*) if just calculating once in a bar, it is ok for small timeframe, but need to wait for long time if we use it at big timeframe like @H4 or @D1.
so i try to use refresh at every Xminutes => OnTimer()
*) i am not sure about the IndicatorCounted() function, still we need it ?

Questions :
*) Is there any clue / idea, which kind of coding tricks can be added here ?
*) Is my idea overlapped each other, or some of it are useless ?

in example, i try to calculate the average of an MA line (using iMAOnArray ... ) , but it seem does not work as expected ...

Any idea to solve this is very appreciate.
Thank you in advance

- lookback candles is not used that way, it's not mentioned in the documentation, but commonly mt4/5 developers will use the quantity of lookback, to refer to how many previous candles are required to be calculated for some condition at a candle, eg a ma crossover would require a lookback of 1, because the candle i and the previous candle i+1 would need the 2 ma lines to be on either side of each other then cross over
- lookback if greater than 0 would need to be involved when calculating the entire chart history, so that calculations start on candle bar-1-1, and not bar-1, eg 50 bars on chart, last index is bar i=49, but you would need a lookback of 1, so you'd start checking conditions from bar 49-1=48

- I'd recommend this alternative to replace what you have, everything is in 1 place

- that is used in older mt4 indicators, it is replaced with the oncalculate parameter of prev_calculated, which is the number of bars calculated on the previous call of oncalc
- on indicator loading, or the chart history has updated, the prev_calc is set to 0
- on every new tick, prev_calc is the value of rates_total which is the number of rates or bars on the chart at the time of the previous oncalc event
- to prevent calculating the entire chart history on every new tick, use the value of prev_calc to decide how many bars to calculate from, see attached indicator for how limit is determined
- uncomment the printouts I included to show the prevcalc values

- look at other existing and commonly used indicators to see how things are typically done, or the attached.

There are several issues so just refer to the attached indicator example.