Fatal error: Allowed memory size when adding new gravity forms

@cyri there could also be something going on with your PHP setup in general, not just plugin related. It does seem like a lot of memory to be using and there aren't any known issues with Gravity Forms causing this type of problem so it's most likely something unrelated to Gravity Forms as other people would be reporting the issue if it was a bug.

In some instances you can increase the memory limit for WordPress via the wp-config.php file. This may help, but it depends on how much is allotted by your web host.

Increasing memory allocated to PHP

Also released with Version 2.5, the WP_MEMORY_LIMIT option allows you to specify the maximum amount of memory that can be consumed by PHP. This setting may be necessary in the event you receive a message such as "Allowed memory size of xxxxxx bytes exhausted".

This setting increases PHP Memory only for WordPress, not other applications. By default, WordPress will attempt to increase memory allocated to PHP to 32MB (code is at beginning of wp-settings.php), so the setting in wp-config.php should reflect something higher than 32MB.

Please note, this setting may not work if your host does not allow for increasing the PHP memory limit--in that event, contact your host to increase the PHP memory limit. Also, note that many hosts set the PHP limit at 8MB.

Increase PHP Memory to 64MB

define('WP_MEMORY_LIMIT', '64M');

Increase PHP Memory to 96MB

define('WP_MEMORY_LIMIT', '96M');

http://codex.wordpress.org/Editing_wp-config.php