curious why composer needs >1,6GB of memory to install 1MB source code

I am not really familiar with composer and using it. I wanted to give it a try, migrating some data from magento 1.9 to 2.3.

Added the repo with this
`php -d allow_url_fopen=1 ../composer-1.phar config repositories.data-migration-tool git https://github.com/magento/data-migration-tool --no-plugins`

executed this:
```
export COMPOSER_MEMORY_LIMIT=-1
php -d allow_url_fopen=1 -d disable_functions=none ../composer-1.phar require magento/data-migration-tool:2.4.1
```
Getting this error:
```
[ErrorException]
proc_open(): fork failed - Cannot allocate memory
```

Looking at top during this I see it grabbing 1.6GB RES memory. Why would installing a 1MB package require this????

Start by reproducing the reported `composer-1.phar require magento/data-migration-tool:2.4.1` command with the shown PHP options and `COMPOSER_MEMORY_LIMIT=-1`. Inspect the `proc_open(): fork failed - Cannot allocate memory` failure and memory usage during installation. Done means identifying whether the memory demand is caused by this package or the Composer installation process and documenting a verified resolution.

Written by the indexing model from the issue text.