(Help) Help optimize code

Hello,

I have a memory (RAM) problem with a section of code.
I want to get the close of the next M5 bar while I'm on a M15 timeframe, so :

Code:

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iClose(pair,5,iBarShift(pair,5,iTime(pair,0,i-1),true)-1)

---

The problem is that it use lot of mermory (about 1GB more than a simple next close of M15 bar), probably because I use it on multiple pairs and deep history in the same indicator.
Does anyone have a solution for optimize this code ?
Thank you.

(Help) Help optimize code