diff --git a/crap/eq_const.h b/crap/eq_const.h
index 4dbd7b4..dd9e995 100644
--- a/crap/eq_const.h
+++ b/crap/eq_const.h
@@ -1,7 +1,5 @@
 #include <string.h>
 
-#include "util.h"
-
 #define ID 0x0DEFACED
 #define LABEL "crap_eq_const"
 #define NAME "crap Constant Equalizer"
@@ -9,45 +7,59 @@
 #define COPYRIGHT "MIT"
 #define PARAMETERS 0
 
+#define BLOCK_SIZE 256
+
+#include "util.h"
+
 #define BANDS 12
 typedef struct {
 	biquad filters[2][BANDS];
 } personal;
 
-INNER double
-process_one(biquad *filters, double samp)
-{
-	for (int i = 0; i < BANDS; i++)
-		samp = biquad_run(&filters[i], samp);
-	return samp;
-}
-
-INNER void
-process(personal *data,
-    float *in_L, float *in_R,
-    float *out_L, float *out_R,
-    unsigned long count)
-{
-	disable_denormals();
-	for (unsigned long pos = 0; pos < count; pos++) {
-		out_L[pos] = process_one(data->filters[0], in_L[pos]);
-		out_R[pos] = process_one(data->filters[1], in_R[pos]);
-	}
-}
-
-INNER void
+static void
 process_double(personal *data,
     double *in_L, double *in_R,
     double *out_L, double *out_R,
-    unsigned long count)
+    ulong count)
 {
 	disable_denormals();
-	for (unsigned long pos = 0; pos < count; pos++) {
-		out_L[pos] = process_one(data->filters[0], in_L[pos]);
-		out_R[pos] = process_one(data->filters[1], in_R[pos]);
+
+	double buf[2*BLOCK_SIZE];
+
+	biquad *f0, *f1;
+
+	for (ulong pos = 0; pos < count; pos += BLOCK_SIZE) {
+		ulong rem = BLOCK_SIZE;
+		if (pos + BLOCK_SIZE > count)
+			rem = count - pos;
+
+		for (ulong i = 0; i < rem; i++) {
+			buf[i*2+0] = in_L[i];
+			buf[i*2+1] = in_R[i];
+		}
+
+		f0 = data->filters[0];
+		f1 = data->filters[1];
+		for (ulong i = 0; i < BANDS; i++) {
+			biquad_run_block_stereo(f0, f1, buf, rem);
+			f0++;
+			f1++;
+		}
+
+		for (ulong i = 0; i < rem; i++) {
+			out_L[i] = buf[i*2+0];
+			out_R[i] = buf[i*2+1];
+		}
+
+		in_L += BLOCK_SIZE;
+		in_R += BLOCK_SIZE;
+		out_L += BLOCK_SIZE;
+		out_R += BLOCK_SIZE;
 	}
 }
 
+#include "process.h"
+
 INNER void
 construct(personal *data)
 {}
@@ -70,7 +82,7 @@ pause(personal *data)
 {}
 
 INNER void
-adjust(personal *data, unsigned long fs)
+adjust(personal *data, ulong fs)
 {
 	biquad *filters = data->filters[0];
 	filters[ 0] = biquad_gen(FILT_PEAKING,  62.0,  5.3, 0.55, fs);
diff --git a/crap/tube.h b/crap/tube.h
index 2d0e646..159fec9 100644
--- a/crap/tube.h
+++ b/crap/tube.h
@@ -2,10 +2,6 @@
 #include <string.h>
 #include <stdio.h>
 
-#include "util.h"
-#include "param.h"
-#include "os2piir.h"
-
 #define ID 0x50F7BA11
 #define LABEL "crap_tube"
 #define NAME "crap Tube Distortion"
@@ -17,7 +13,9 @@
 #define BLOCK_SIZE 256
 #define FULL_SIZE (BLOCK_SIZE*OVERSAMPLING)
 
-typedef unsigned long ulong;
+#include "util.h"
+#include "param.h"
+#include "os2piir.h"
 
 typedef struct {
 	double desired, actual, speed;
@@ -61,7 +59,7 @@ process_one(double x, double drive, double wet)
 	return (distort(x*drive)/drive*0.79 - x)*wet + x;
 }
 
-INNER void
+static void
 process_double(personal *data,
     double *in_L, double *in_R,
     double *out_L, double *out_R,
diff --git a/include/util.h b/include/util.h
index 49a9890..a443eb6 100644
--- a/include/util.h
+++ b/include/util.h
@@ -5,6 +5,7 @@
 #endif
 
 #define INNER static inline
+typedef unsigned long ulong;
 
 INNER void
 disable_denormals();
diff --git a/include/util_def.h b/include/util_def.h
index 10814dd..5a5c921 100644
--- a/include/util_def.h
+++ b/include/util_def.h
@@ -48,7 +48,7 @@ design(double cw, double sw,
 	};
 }
 
-INNER biquad
+static biquad
 biquad_gen(filter_t type, double fc, double gain, double bw, double fs)
 {
 	double w0, cw, sw, A, As, Q;
@@ -102,3 +102,54 @@ biquad_run(biquad *bq, double x)
 
 	return y;
 }
+
+INNER void
+biquad_run_block_stereo(biquad *bq_L, biquad *bq_R,
+    double *buf, ulong count)
+#ifdef __SSE2__
+{
+	__m128d b0, b1, b2, a1, a2, x1, x2, y1, y2;
+
+	b0 = _mm_set1_pd(bq_L->b0);
+	b1 = _mm_set1_pd(bq_L->b1);
+	b2 = _mm_set1_pd(bq_L->b2);
+	a1 = _mm_set1_pd(bq_L->a1);
+	a2 = _mm_set1_pd(bq_L->a2);
+
+	x1 = _mm_setr_pd(bq_L->x1, bq_R->x1);
+	x2 = _mm_setr_pd(bq_L->x2, bq_R->x2);
+	y1 = _mm_setr_pd(bq_L->y1, bq_R->y1);
+	y2 = _mm_setr_pd(bq_L->y2, bq_R->y2);
+
+	for (int i = 0; i < 2*count; i += 2) {
+		__m128d x = _mm_load_pd(buf + i);
+		__m128d y = b0*x + b1*x1 + b2*x2 + a1*y1 + a2*y2;
+		x2 = x1;
+		y2 = y1;
+		x1 = x;
+		y1 = y;
+		_mm_store_pd(buf + i, y);
+	}
+
+	double temp[8];
+	_mm_store_pd(temp+0, x1);
+	_mm_store_pd(temp+2, x2);
+	_mm_store_pd(temp+4, y1);
+	_mm_store_pd(temp+6, y2);
+	bq_L->x1 = temp[0];
+	bq_R->x1 = temp[1];
+	bq_L->x2 = temp[2];
+	bq_R->x2 = temp[3];
+	bq_L->y1 = temp[4];
+	bq_R->y1 = temp[5];
+	bq_L->y2 = temp[6];
+	bq_R->y2 = temp[7];
+}
+#else
+{
+	for (ulong i = 0; i < 2*count; i += 2) {
+		buf[i+0] = biquad_run(bq_L, buf[i+0]);
+		buf[i+1] = biquad_run(bq_R, buf[i+1]);
+	}
+}
+#endif