I have a big PSD file that I need to export to .PNG. It has a lot of texts inside and I need to edit them very fast and possible without loading the PSD file since it will eat my memory.
The thing is I'm a noob at scripting or anything like this.
So, Simple text editor of a PSD without loading the PSD and auto save to .PNG with the same name in same directory.
A PSD file will not eat your memory when your not editing it. So you can save a PNG file and use it with applications like browsers and you can save a PSD file to preserver your text layers so you can edit them in the future.
Have you actually opened the document into Photoshop and discovered your memory to be "eaten" in some harmful way. Your computer's memory is there to be temporarily used, so why do you not want it to be used?
Text layers are very small unless its a copy of a large book. PNG files do not support Text layers they more or less have a single pixel layer and an alpha channel layer. Text layers are small a few characters and font name and settings like size style etc. the are drawn with vector graphics. Yes ever layer use in Photoshop requires some memory. When memory runs short Photoshop uses scratch space on disk. Photoshop power come from layer support. If you want a simple program you may want to look at mspaint.
As I wrote you can save two files one for the other programs and one you can edit your not limited to a single file. If all there is is text browsers can display html the had you text. If little color GIF files will be much smaler the PNG files. Most of the time you need more then one file for most applications do not sopport PSD files. There an Adobe thing....