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/Instance running very slowly - not sure on best instance type/

Instance running very slowly - not sure on best instance type


I have an instance that is running very slowly, and users have difficulty getting ssh access, which is very slow.

We suspect it is a memory issue, but not sure, as I have looked on AWS Compute Optimizer, but although every other instance is showing up this one is not (note optimizer has been applied for some months)?

I am interested to understand the issue, and if it is memory, and then I would like a recommendation on which instance type/size is best for this instance - but can't get the details of what elements of the instance are struggling (i.e. memory, network, etc...)?

Any suggestions on what I do next greatly appreciated.


  • It would help a lot to know what type (family) of instance you're using.

2 Answers

It can be a problem with the EC2 instance itself being overloaded or it could also be because of network band-width. Are the users connecting to this instance over the internet or from your corporate network over IPSec VPN or DirectConnect? IPSec VPN has a band-width limitation of around 1.25 Gbps. If using DirectConnect, are you using 1Gbps or 10Gbps? If you are using a transit VPC where you have your network firewall devices and you are connecting to the VCPs using VPN, then also you will be constrained to the 1.25 Gbps even if you are using 10 Gbps Direct Connect. It is possible that other applications are hogging the network band-width. For investigating if the EC2 instance itself is overloaded, you can look at the Cloudwatch metrics -

Likewise, for checking the performance of your IPSec VPN, you can look at Cloudwatch -

answered 16 days ago
  • Thanks for the info. My developers are accessing the instance via SSH (Port 22) using a client - and they are seeing delays in connecting, and activity is very slow. The primary application on this server is processing a data feed, which is connected (via a white listed Elastic IP Address), using a socket connection (w TLS protocol) on a defined port - and this is achieved via a standard IPv4 Network interface... So it is not VPN or DirectConnect (I do not think?) - but it may still be overloading? How do I monitor/check this, please?


If you are positive that the network band-width is not the issue, then you need to look at the Cloudwatch metrics for the EC2 machine in question - and see if it is running high on resources. In that case, you may want to go with a more powerful box.

answered 13 days ago

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