Scripts are being evaluated/run so that we can verify the validity of the given transaction. Depending on the script itself and the implementation, this evaluation could take a much longer time than normally expected.
As a challenge, try to come up with such scripts that could take longer than normal (could be 10 second, minute or hour!). There are also some rare examples out there on the internet from old days that you can find and post here.

• The script doesn't have to be standard but it has to be valid (eg. no disabled OPs).
• It doesn't have to be in a full transaction. It could be as scriptPub, scriptSig and if available redeemScript or witnesses. Or simply 1 script from start to end.
• It should also include the expected time that it takes to evaluate in addition to the device hardware and platform used.

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