Others will probably give additional comments,but
1. In my understanding 'high performance' is a common, often used by factories, description of valves with extended ability to keep thight at higer temperatures and pressures than more common 'standard valves'. I do not know of any standard describing the difference between a common/standard valve and a High Performance valve. High-Performance tends to be a 'factory description' for chemical and petrochemical branches. Loosely the boundary will be where a standard BF centric valve will not function properly, for common smaller sizes perhaps somewhere between 16 to 25 bars. Typical a high performance valve will, as you state, be a double or trippel eccentric construction, with metal to metal seats and at least at 25 -40 bar performance, even if the construction and flanges could be used or certified for lower pressures.
2. Double eccentric valves are well-known both with linings and soft sealings. For instance for drinking water or hydroelectric plants, up to higher pressure classes ( at least 40 bar). Sizes will range from 50mm to 2000mm and more. Temperature range for fluid is normally limited. The valves will not be called or marketed as high-performance valves.
