If you're running Apache (and you probably are), there is a simple built in load test that you can run to get a basic idea of how your site / server will perform. From the command line, you can run...

ab -n 100 -c 10 http://www.greencrescent.com/
  • ab = apache bench
  • n = number of requests
  • c = the number to run concurrently (at the same time)
  • http://www.greencrescent.com/ is the domain we're testing (replace with your target domain)

The output looks like...

root@server [~]# ab -n 100 -c 10 http://www.greencrescent.com/ This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking www.greencrescent.com (be patient).....done Server Software: Apache/2.2.22 Server Hostname: www.greencrescent.com Server Port: 80 Document Path: / Document Length: 33192 bytes Concurrency Level: 10 Time taken for tests: 1.103 seconds Complete requests: 100 Failed requests: 95 (Connect: 0, Receive: 0, Length: 95, Exceptions: 0) Write errors: 0 Total transferred: 3355815 bytes HTML transferred: 3301815 bytes Requests per second: 90.63 [#/sec] (mean) Time per request: 110.335 [ms] (mean) Time per request: 11.033 [ms] (mean, across all concurrent requests) Transfer rate: 2970.20 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 1 Processing: 56 107 40.1 98 251 Waiting: 50 92 26.5 92 229 Total: 56 107 40.1 98 251 Percentage of the requests served within a certain time (ms) 50% 98 66% 106 75% 111 80% 121 90% 188 95% 214 98% 243 99% 251 100% 251 (longest request) 
Options are:
    -n requests     Number of requests to perform
    -c concurrency  Number of multiple requests to make
    -t timelimit    Seconds to max. wait for responses
    -b windowsize   Size of TCP send/receive buffer, in bytes
    -p postfile     File containing data to POST. Remember also to set -T
    -u putfile      File containing data to PUT. Remember also to set -T
    -T content-type Content-type header for POSTing, eg.
                    'application/x-www-form-urlencoded'
                    Default is 'text/plain'
    -v verbosity    How much troubleshooting info to print
    -w              Print out results in HTML tables
    -i              Use HEAD instead of GET
    -x attributes   String to insert as table attributes
    -y attributes   String to insert as tr attributes
    -z attributes   String to insert as td or th attributes
    -C attribute    Add cookie, eg. 'Apache=1234. (repeatable)
    -H attribute    Add Arbitrary header line, eg. 'Accept-Encoding: gzip'
                    Inserted after all normal header lines. (repeatable)
    -A attribute    Add Basic WWW Authentication, the attributes
                    are a colon separated username and password.
    -P attribute    Add Basic Proxy Authentication, the attributes
                    are a colon separated username and password.
    -X proxy:port   Proxyserver and port number to use
    -V              Print version number and exit
    -k              Use HTTP KeepAlive feature
    -d              Do not show percentiles served table.
    -S              Do not show confidence estimators and warnings.
    -g filename     Output collected data to gnuplot format file.
    -e filename     Output CSV file with percentages served
    -r              Don't exit on socket receive errors.
    -h              Display usage information (this message)
    -Z ciphersuite  Specify SSL/TLS cipher suite (See openssl ciphers)
    -f protocol     Specify SSL/TLS protocol (SSL2, SSL3, TLS1, or ALL)