It would be helpful if you specified both your hard- and software environment including exact versions of software used, and statistics and data about the layer you are trying to access, like feature type (point, line, polygon), how many features (10k, 100M??) etc, and what you mean with trying to "load" the data in ArcMap: are you trying to load all of the data at full extent (which effectively renders the use of a spatial index useless), or are you properly accessing the data through well defined min/max display scales (properly limiting the number of features needed to be "loaded" to ArcMap at any given extent and point in time)