python - Calculating shortest distance from point to line using QGIS?

What is the best method to calculate the distance from the nearest road for a series of address points in QGIS, having a very big dataset? (QGIS 2.0.1, Win XP)

I read the answers to previous similar questions:

Measuring the distance between lines and points in QGIS

Drawing perpendicular lines in PyQGIS?

Calculating minimum distance between points and polygons in QGIS?

https://stackoverflow.com/questions/16448402/distance-of-point-feature-to-nearest-polygon-in-r

Nevertheless:

1. 
   
   

   MMQGIS plugin find the disance to the nearest node of a line network, not the shortest (perpendicular) distance to a line.

   
   


2. 
   

   R and Python proposed scripts correctly works for small datasets and can be implemented in the modeler, however for my job I have 530 points and a regional street layer with about 135'000 features, and cycling through all the features then taking the shortest distance for all points will take an enormous amount of time

   
   


3. 
   

   I have problems in making GRASS work in QGIS 2.0.1 (GRASS in QGIS not working (windows XP)).