High variance in page load time

Hello,

Re: Staging website https://mbaadmissiongurus.com/staging

ref: Testing pageload time using https://tools.pingdom.com/

When test various pages of the above staging site for page load time using Pingdom, We find massive fluctuations. At first instance of test, some pages have PLT of 3+ seconds . Once I reload the Pingdom tool and test the same page again, the PLT is as low as 0.5-0.8 (desired). Some details here

The staging website uses an IP redirect plugin
The above issue is not seen on the live website https://www.mbaadmissiongurus.com that does not have the said plugin
Can you please advise us on the possible causation??

Thank You

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