I was using the most recent distributed version of RStudio. Tried reinstalling it but got the same problem on two different machines (Mac Pro with 3.7 Ghtz Quad Core Xenon E5 with 32 GB RAM and MacBook Pro with an 2.9 Mhtz Intel i7 and 16GB RAM). Both machines resulted in the same problem
The dataset was a matrix of numeric data (about 2400 x 2400) imported from either a text of Excel file using readr. When loaded by the View function, the CPU maxed out for minutes at a time. Typing a single character on the command line resulted in more churning by the CPU. Closing the viewer solved the churning problem but made this version of RStudio less effective for what I needed to accomplish. The problem occurred whether the data were treated as a numeric matrix, a dataframe or a tibble.
Rolling back RStudio to Version 1.0.153 solved the problem. The matrix loads up without any problem. This allowed me to run the analysis I needed to complete.
I have not yet tried the preview version, but will in a few days, when I can revisit this analysis.