Are both the NR machine and your PC on a local network?
Are other UI nodes slow too?
try importing this flow and pressing the button and switch. the text should show them going on and off.
[{"id":"497c5c0c.084fa4","type":"ui_switch","z":"400c8386.3b0104","name":"","label":"switch","tooltip":"","group":"dcf2fce6.0eb518","order":8,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"","style":"","onvalue":"switch on","onvalueType":"str","onicon":"","oncolor":"","offvalue":"switch off","offvalueType":"str","officon":"","offcolor":"","x":260,"y":100,"wires":[["a742f7f6.d6fa68"]]},{"id":"76a28525.38cd54","type":"ui_button","z":"400c8386.3b0104","name":"","group":"dcf2fce6.0eb518","order":9,"width":0,"height":0,"passthru":true,"label":"button","tooltip":"","color":"","bgcolor":"","icon":"","payload":"button on","payloadType":"str","topic":"","x":260,"y":180,"wires":[["e846660b.21b03"]]},{"id":"a742f7f6.d6fa68","type":"ui_text_input","z":"400c8386.3b0104","name":"","label":"","tooltip":"","group":"dcf2fce6.0eb518","order":10,"width":0,"height":0,"passthru":true,"mode":"text","delay":300,"topic":"","x":440,"y":100,"wires":[[]]},{"id":"5a520acd.38d1fc","type":"ui_text_input","z":"400c8386.3b0104","name":"","label":"","tooltip":"","group":"dcf2fce6.0eb518","order":11,"width":0,"height":0,"passthru":true,"mode":"text","delay":300,"topic":"","x":580,"y":180,"wires":[[]]},{"id":"e846660b.21b03","type":"function","z":"400c8386.3b0104","name":"","func":"// initialise the counter to 0 if it doesn't exist already\nvar count = context.get('count')||0;\ncount = Math.abs(count-1);\n// store the value back\ncontext.set('count',count);\n// make it part of the outgoing msg object\nmsg.count = count;\nnode.warn(\"count=\"+count);\nmsg.payload = (count > 0) ? \"button on\":\"button off\";\nreturn msg;","outputs":1,"noerr":0,"x":430,"y":180,"wires":[["5a520acd.38d1fc"]]},{"id":"dcf2fce6.0eb518","type":"ui_group","z":"","name":"Default","tab":"df3f2d27.786758","disp":true,"width":"6","collapse":false},{"id":"df3f2d27.786758","type":"ui_tab","z":"","name":"Home","icon":"dashboard","disabled":false,"hidden":false}]