Thanks to its free licensing and the development of initiatives like Bioconductor, R has become an essential part of the bioinformatics toolbox in the past years and is more and more confronted with genomically located data. While separate solutions are available to manipulate and visualize such data, no R package currently offers the efficiency required for computationally intensive tasks such as interactive genome browsing. The package proposed here fulfills this specific need, providing a multilevel interface suitable for most needs, from a completely interfaced genome browser to low-level classes and methods. Its time and memory efficiency have been challenged in a human dataset, where it outperformed existing solutions by several orders of magnitude.