<p>I can't be sure why your client specifically took 15 minutes to start. But I have benchmarked the client's startup process. Most of the time is spent validating the database to ensure the client has a sensible view of the hash chain.</p>

<p>It is "fast verified" up to the most recent checkpoint and then "slow verified" to the current block. Fast verification entails checking only that the header is valid. Slow verification is a much more complete verification that can only be done at about 20 blocks per second on hardware like yours. (Upgrading the client will help, since newer version of the client will have more recent checkpoints.)</p>

<p>If you passed the <code>-rescan</code> option, the client will check every transaction in every block to see if it relates to any account in your wallet. That will add some time to the client's startup time.</p>

<p>When you run the Bitcoin client for the very first time, it will take several hours to sync up to the network. The downside of a decentralized system is that you cannot trust anything and must check everything yourself. This literally requires you to fully verify <em>every</em> Bitcoin transaction that has ever taken place. I've seen that take 9 hours on Pentium 4 class computers with 100Mbps Internet connections. (Though I think it should be a bit faster now, thanks to bugfixes in the client.)</p>

CC BY-SA 3.0
2011-11-07T03:10:43.357Z
Is there any flag that shows a verbose output of what the client is doing?
nmat
CC BY-SA 3.0
2011-11-07T03:12:29.627Z
You can check the 'debug.log' file. On Ubuntu `tail -f ~/.bitcoin/debug.log` should show it to you.
David Schwartz
CC BY-SA 3.0
2011-11-06T07:42:19.920Z
2011-11-06T14:19:58.643Z
2011-11-06T14:19:58.643Z
David Schwartz
<p>Maybe you are mining?
From my experience, when I run the miner before bitcoin,
bitcoin will block at "Loading address..." or "Loading block index..." for a long time.
You can see it in debug.log.
Stop the miner and bitcoin will start soon. Then you can run the miner again.</p>

CC BY-SA 3.0
2011-11-12T12:14:53.363Z
No mining here, as far as I know.  Thanks. I ll check my debug.log file and post it here soon.
H_7
CC BY-SA 3.0
2011-11-07T12:02:33.143Z
2011-11-07T12:02:33.143Z
yongjhen
<p>I've been evaluating some bitcoin clients and my nastiest one; bitcoin-qt on a ten year old single-core 32-bit intel with 512MB RAM has been struggling all week and it has still only got to 22GB of 34GB of the blockchain loaded.</p>

<p>This morning after it crashed, the next restart required "rescan" which took an hour before it could resume downloading the full blockchain.</p>

<p>I've had much better luck with Electrum (bitcoin wallet application; without the whole blockchain) which works fine on both the 512MB singlecore and on the 1024MB quadcore raspberryPi.  That starts up in 1 to 2 minutes.</p>

CC BY-SA 3.0
2015-07-23T12:21:46.683Z
Please read up on how this site works. In short: Questions and Answers. You replied to an 4 year old question but it's not a reply to the question at all. Slowness on an ancient 32bit PC with insufficient memory is not surprising at all. Also, comparing it to Electrum is apples to oranges.
Jannes
CC BY-SA 3.0
2015-07-24T00:08:03.980Z
This question was about starting the client,  your answer is about  synchronization. There certainly would be a question somewhere along the lines of "how long does synchro take" that would be a better match.
Murch
CC BY-SA 3.0
2015-07-22T17:59:22.553Z
2015-07-22T17:59:22.553Z
mephisto
<p>I use Ubuntu 11.10 and have recently installed the standard Bitcoin client 0.40. But the GUI only appear around 15 minutes after started. My machine is an AMD64 Athlon 4600x2 with 6GB RAM. Is this normal? (I don't think so) Any idea?</p>

CC BY-SA 3.0
2011-11-06T01:21:05.350Z
This also happened to me, but I never really looked into it. Although 15 minutes seems a little too much. My GUI appeared after 5 minutes or so. I was using Ubuntu 10.10 at the time and the client version 0.4.
nmat
CC BY-SA 3.0
2011-11-06T01:30:04.643Z
I think 5 minutes stills so much.
H_7
CC BY-SA 3.0
2011-11-06T03:01:03.460Z
What command-line options are you passing? If, for example, you pass '-rescan', this is not unusual.
David Schwartz
CC BY-SA 3.0
2011-11-06T12:58:41.240Z
David, unfortanelly, I don't have yet a near half-quarter of the linux knowledge that you have, so to find the launcher of the gui to me stills hard complicated. I apologize for this, but all I did was adding the bitcoin client to the startup aplications. I started early just double-clicking the icon, _bitcoin_ or _bitcoind_.  Because of the 15 minutes delay to show **GUI**, I even don't know yet where this 2 programs differ. Sorry for some bad english too. **=)** Well, I think no command-line options here.
H_7
<bitcoin-core>
Why does it take 15 minutes for my Bitcoin client to start?
H_7
# Why does it take 15 minutes for my Bitcoin client to start?

(Asked by: username_0 on 2011-11-06)

I use Ubuntu 11.10 and have recently installed the standard Bitcoin client 0.40. But the GUI only appear around 15 minutes after started. My machine is an AMD64 Athlon 4600x2 with 6GB RAM. Is this normal? (I don't think so) Any idea?

**Tags:** bitcoin-core

> **Comments:**
> **username_1**: This also happened to me, but I never really looked into it. Although 15 minutes seems a little too much. My GUI appeared after 5 minutes or so. I was using Ubuntu 10.10 at the time and the client version 0.4.  
> **username_0**: I think 5 minutes stills so much.  
> **username_2**: What command-line options are you passing? If, for example, you pass '-rescan', this is not unusual.  
> **username_0**: username_2, unfortanelly, I don't have yet a near half-quarter of the linux knowledge that you have, so to find the launcher of the gui to me stills hard complicated. I apologize for this, but all I did was adding the bitcoin client to the startup aplications. I started early just double-clicking the icon, _bitcoin_ or _bitcoind_.  Because of the 15 minutes delay to show **GUI**, I even don't know yet where this 2 programs differ. Sorry for some bad english too. **=)** Well, I think no command-line options here.  

---

## 3 answers

### Answer by username_2 on 2011-11-06. Score: 6

I can't be sure why your client specifically took 15 minutes to start. But I have benchmarked the client's startup process. Most of the time is spent validating the database to ensure the client has a sensible view of the hash chain.

It is "fast verified" up to the most recent checkpoint and then "slow verified" to the current block. Fast verification entails checking only that the header is valid. Slow verification is a much more complete verification that can only be done at about 20 blocks per second on hardware like yours. (Upgrading the client will help, since newer version of the client will have more recent checkpoints.)

If you passed the `-rescan` option, the client will check every transaction in every block to see if it relates to any account in your wallet. That will add some time to the client's startup time.

When you run the Bitcoin client for the very first time, it will take several hours to sync up to the network. The downside of a decentralized system is that you cannot trust anything and must check everything yourself. This literally requires you to fully verify *every* Bitcoin transaction that has ever taken place. I've seen that take 9 hours on Pentium 4 class computers with 100Mbps Internet connections. (Though I think it should be a bit faster now, thanks to bugfixes in the client.)

> **Comments:**
> **username_1**: Is there any flag that shows a verbose output of what the client is doing?  
> **username_2**: You can check the 'debug.log' file. On Ubuntu `tail -f ~/.bitcoin/debug.log` should show it to you.  

---

### Answer by username_3 on 2011-11-07. Score: 1

Maybe you are mining?
From my experience, when I run the miner before bitcoin,
bitcoin will block at "Loading address..." or "Loading block index..." for a long time.
You can see it in debug.log.
Stop the miner and bitcoin will start soon. Then you can run the miner again.

> **Comments:**
> **username_0**: No mining here, as far as I know.  Thanks. I ll check my debug.log file and post it here soon.  

---

### Answer by username_4 on 2015-07-22. Score: -2

I've been evaluating some bitcoin clients and my nastiest one; bitcoin-qt on a ten year old single-core 32-bit intel with 512MB RAM has been struggling all week and it has still only got to 22GB of 34GB of the blockchain loaded.

This morning after it crashed, the next restart required "rescan" which took an hour before it could resume downloading the full blockchain.

I've had much better luck with Electrum (bitcoin wallet application; without the whole blockchain) which works fine on both the 512MB singlecore and on the 1024MB quadcore raspberryPi. That starts up in 1 to 2 minutes.

> **Comments:**
> **username_5**: Please read up on how this site works. In short: Questions and Answers. You replied to an 4 year old question but it's not a reply to the question at all. Slowness on an ancient 32bit PC with insufficient memory is not surprising at all. Also, comparing it to Electrum is apples to oranges.  
> **username_6**: This question was about starting the client,  your answer is about  synchronization. There certainly would be a question somewhere along the lines of "how long does synchro take" that would be a better match.  

---

