I think that a review of the CRR and CRD IV, as is currently taking place in the EU, is a good place to start. For instance, in its proposal for a CRR II and CRD V, the European Commission expressed its intention to reduce the burden on smaller institutions in all reform areas.
The draft consultative document contains various relief measures and de minimis thresholds, such as in disclosure and reporting requirements and in trading book regulation. Institutions below these thresholds would be subject to simplified rules, with some requirements even being abolished altogether. This would mean, for instance, that small institutions that do little proprietary trading would not be subject to the new, complicated rules.