As described in Berekenen duurt >15 minuten met Invantive Control formule Exact Online budget I_EOL_BGT_PDE_LINE_AMOUNT, the formulas for Exact Online budgets do not increase speed as the balance formulas for Exact Online do.
The Exact Online balance formulas typically take 1 ms per non-cached invocation in high volumes (1.000 and more). The Exact Online budget formulas typically take 200 ms per non-cached invocation in high volumes.
Suggestion is to apply the same or similar optimizations on the budget formules as on balance formulas, increasing speed up to a factor 200x in intense use scenarios.
Another related idea on budget formula is Excel formula with cost center and cost unit for Exact Online budget.