Disabling the IPv6 may speed up an internet connection under certain conditions. Internet currently uses the IPv4 protocol for IP addresses. The IPv6 is the next generation of the internet and is aimed to solve many problems associated with IPv4 such as number of IP addresses, quality of service, security and many more. Most operating systems such as Windows Vista and Linux support the IPv6. Internet browsers such as Mozilla Firefox searches for the IP address of the website through IPv6 first. This adds a little delay as almost all IP addresses in the web are IPv4. Therefore, disabling the IPv6 may help to speed up internet access.
Disabling IPv6 will speed up Internet connections.
True, but only under certain circumstances.
Internet currently uses the IPv4. The next generation (Internet 2) are using IPv6 (higher). IPv6 will solve many problems endemic to IPv4 (number of IP address, security, quality of service, etc.). The transition to IPv6 is inevitable, but it will take some time.
The good news is that most current operating systems (Windows Vista, Linux...) are already perfectly capable of working in IPv6.
IPv6 is "better" than IPv4; as both are available, then the logical step to take is to firstly use IPv6.
And that's what most software does: They will first try to use IPv6 (if present in the operating system), then back to IPv4 if their application fails to use IPv6.
E.g. when using Firefox: When you enter the address of a website, Firefox will first try to find the IP address (DNS name) via IPv6. If the operation fails the procedure is repeated using IPv4.
In theory, it sounds good, as the day when IPv6 is active, the software will work automatically with no need to be reconfigured.
In practice, waiting in vain for a response DNS IPv6 adds a small unnecessary delay (since currently almost no provider offers IPv6 access, except private networks or experimental).
This choice between IPv6 and IPv4 software is made by software.
This is not a problem with IPv6, the problem is due to software, choosing protocols poorly adapted to the situation.
In the case of software that supports both IPv4 and IPv6, or in cases where IPv6 routing tables are well configured, the presence of IPv6 causes absolutely no slowdown.
Disabling the IPv6 support.
In Firefox, type in the address bar: about: config In the filter, type: ipv6 You will see the variable network.dns.disableIPv6 Change value to true to disable IPv6 support in Firefox.
Note that: For software where there is no option to disable IPv6, it will be necessary to disable IPv6 directly from the operating system.
Learn how disable IPv6 support in Ubuntu Debian: Disabling IPv6 support