Quick and fast? Try Preview, which has extremely powerful editing tools:
- Resize — free form or aspect ratio maintain
- Crop selection — select: rectangular, oval, smart lasso, or free form
- Rotate — Left, Right
- Flip — Horizontal, Vertical
- Adjust Color Gamut dynamically
- Adjust Exposure
- Adjust Contrast
- Adjust Color Saturation
- Adjust Color Temperature
- Adjust Tint
- Convert to and adjust Sepia tone
- Adjust Sharpness
- Set Printer and monitor Color synching
Apple Preview Image Adjustment Palette
In addition, all images can be converted to a host of other image file types:
Apple Preview Image Conversion Choices
Add to that the ability to quickly annotate an image by adding an Arrow, a Rectangular Box, a Circle or an Oval, and Text. Preview can free-form crop any picture:
Preview can import images from any connected camera, iPhone, scanner, or it can grab a screen, a window, or a selected area of the screen. It can email any image using its integration with Apple's Mail app.
All of that is just in a system utility Apple originally designed to simply Preview images. iPhoto has tons more capability.
You need to quit being annoyed at iPhoto and start exporing its capabilities which you will find probably exceed those of IrfanView, especially in the latest version which incorporated many professional level tools from Apple's professional photography application Aperture. There is a reason why Apple is touted for handling photos.