DPI is samples per inch — more pixels, more RAM, more ZIP weight
A US letter page at ~96 DPI is about 816 × 1056 pixels. At 300 DPI it is about 2550 × 3300. That is roughly 9× the pixels and a much heavier PNG. UI designers extract icons; print vendors want a raster proof that still shows 0.25 pt rules. Convertify4u’s Pro HD path runs that rasterization on Hetzner VPS because a phone tab will OOM. PNG remains lossless versus JPEG: no 8×8 block ringing on type. It is still a bitmap — you cannot recover a font file from the pixels. Alpha: useful when the PDF page or object actually has transparency; a white page stays white. Run a one-page sample before an entire archive. Pair with the presentations spoke for social/web sizes that do not need 300 DPI. Eligible screen-DPI jobs stay on the free hub; this spoke is the paid fidelity upgrade via Lemon Squeezy.
When 300 DPI is wasted
Instagram carousels and CMS heroes do not need print density. You will only create a slow ZIP. Use standard Edge, then resize.
When 300 DPI is justified
Vendor preflight, CAD sheets with tiny dimensions, logo cutouts that will be placed on colored backgrounds, archival captures of a designed page.