<p><a href="https://blockchain.info/tx/bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08" rel="nofollow noreferrer">bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08</a> is usually the transaction referred to as being the megatransaction that took seconds to verify. It is the only non-coinbase transaction in block <a href="https://blockchain.info/block/000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe" rel="nofollow noreferrer">000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe</a>.</p>

<p>Nowadays this transaction is verified much faster than 20 seconds. Last time I benchmarked this, it was ~1 second. With the introduction of <code>assumevalid</code> in Bitcoin Core 0.14, the transaction's signatures are no longer fully validated so it takes the same time as most other blocks, ~60 milliseconds.</p>

CC BY-SA 3.0
2017-09-27T05:46:45.880Z
2017-09-27T05:46:45.880Z
Ava Chow
<p>I'm not completely sure if this is what you are looking for, but it may be.</p>

<p>Here you have a type of transaction that takes 3 minutes to verify, and that was reported back in 2013. (<a href="https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2013-2292" rel="nofollow noreferrer">CVE-2013-2292</a>). Moreover, in <a href="https://bitslog.wordpress.com/2017/01/08/a-bitcoin-transaction-that-takes-5-hours-to-verify/" rel="nofollow noreferrer">Sergio Demian Lener's blog</a> you can find a related topic, where he explains how he found a vulnerability that used the <code>FindAndDelete</code> function and <code>OP_CODESEPARATOR</code> to create a transaction that toke up more than 5 hours to verify.</p>

CC BY-SA 3.0
2017-09-26T14:56:47.043Z
2017-09-26T14:56:47.043Z
sr_gi
<p>I heard that there was an old block with one transaction and it takes 20 seconds of CPU time to verify.</p>

<p>1) Which block was it? I forgot its block height.</p>

<p>2) Is there a block that takes more time to verify? Or is there a similar block?</p>

<blockchain><block>
Longest-time-verifying block
MCCCS
# Longest-time-verifying block

(Asked by: username_0 on 2017-09-26)

I heard that there was an old block with one transaction and it takes 20 seconds of CPU time to verify.

1) Which block was it? I forgot its block height.

2) Is there a block that takes more time to verify? Or is there a similar block?

**Tags:** blockchain, block


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## 2 answers

### Answer by username_1 on 2017-09-27. Score: 1 | Accepted answer

[bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08](https://blockchain.info/tx/bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08) is usually the transaction referred to as being the megatransaction that took seconds to verify. It is the only non-coinbase transaction in block [000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe](https://blockchain.info/block/000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe).

Nowadays this transaction is verified much faster than 20 seconds. Last time I benchmarked this, it was ~1 second. With the introduction of `assumevalid` in Bitcoin Core 0.14, the transaction's signatures are no longer fully validated so it takes the same time as most other blocks, ~60 milliseconds.


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### Answer by username_2 on 2017-09-26. Score: 2

I'm not completely sure if this is what you are looking for, but it may be.

Here you have a type of transaction that takes 3 minutes to verify, and that was reported back in 2013. ([CVE-2013-2292](https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2013-2292)). Moreover, in [Sergio Demian Lener's blog](https://bitslog.wordpress.com/2017/01/08/a-bitcoin-transaction-that-takes-5-hours-to-verify/) you can find a related topic, where he explains how he found a vulnerability that used the `FindAndDelete` function and `OP_CODESEPARATOR` to create a transaction that toke up more than 5 hours to verify.


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