removed UPDATE_INTERVAL, it is neat to have it but removing it is a tradeoff worth making, because the clock would act weird if this used to work with cpu_perc().

config.def.h

@@ -8,9 +8,6 @@
 #define BATTERY_NOW	"energy_now"
 #define BATTERY_FULL	"energy_full_design"
 
-/* bar update interval in seconds (smallest value = 1) */
-#define UPDATE_INTERVAL	1
-
 /* text to show if no value can be retrieved */
 #define UNKNOWN_STR	"n/a"
 

slstatus.c

@@ -147,7 +147,6 @@ cpu_perc(void)
 	fscanf(fp, "%*s %Lf %Lf %Lf %Lf", &a[0], &a[1], &a[2], &a[3]);
 	fclose(fp);
 
-	/* wait a second (for avg values) */
 	sleep(1);
 
 	fp = fopen("/proc/stat","r");
@@ -637,7 +636,6 @@ main(void)
 
 		XStoreName(dpy, DefaultRootWindow(dpy), status_string);
 		XSync(dpy, False);
-		sleep(UPDATE_INTERVAL -1);
 	}
 
 	/* NOT REACHED */