Closing periods only means data can no longer be changed,
@Prahar Tiwari. I believe it has no influence on calculation times, but I'll defer the confirmation to the Apptio experts in performance, as per @Claudia Secco above.
What might help is reducing the report calculation window: this might shorten calculation times somewhat, at the cost of having to wait if you want data from periods outside that window. My understanding is that Apptio will still calculate tables, metrics and models, but not reports.
We extract every year the most significant data from the last FY and then move the window to keep up to 2 years' worth of data. We load that data to a set of tables, and we have a
Historical Data report that supports the most habitual queries. True, we don't have everything, but it works for us.
#ApptioforAll