How to update a single composer package?

I know that I can use composer update vendor/package but here's my case.

Composer is very slow when updating, I have around 6 packages installed and one local vcs package being loaded from a local folder. When I run composer update even for that specific local package, composer connects to Packagist to look for other updates and this process is very slow, I don't know if it's my computer or my internet. Is there a way I can tell composer to just update the package from local folder when I run composer update local/package without contacting Packagist and running through all the heavy json files it downloads?

Note: I know how to load a local composer package. It's loading perfectly, it's just that I'm looking for a way to tell composer just to load the local package without contacting Packagist.

"repositories": [
   {
     "type": "vcs",
     "url": "../local/package"
   }
],

My problem is that it's slow to contact Packagist. Running composer update local/package -vvv Shows that it still downloads json files from packagist even if it's told to update just local/package.

Solution

There are multiple ways of speeding the Composer fetch up:

define a custom repo, which points to a local path and install with --prefer-source
```
"repositories": [
    {
        "type":"vcs",
        "url":"/path/to/your/local/package/packageA"
    }
],
"require":{
    "package/packageA" : "dev-master"
}
```
Follow-up trick: if you exactly know the type of the repo, then specify it!

In other words: do not use "type":"vcs" if you can specify "type":"git" or "type":"svn". Composer will skip running through all the repo adapters to figure the correct one out.
you could setup Satis and define only the required packages for your project and their dependencies ("require-dependencies": "true"). This acts as a package proxy in front of packagist. You would simply fetch from the local Satis mirror/proxy.

Give this a try, to disable the default Packagist repository:

{
    "repositories": [
        {
            "packagist": false
        }
    ]
}