diff --git a/eth/tracers/live/perf.go b/eth/tracers/live/perf.go
index 51c6861987..bda674d34f 100644
--- a/eth/tracers/live/perf.go
+++ b/eth/tracers/live/perf.go
@@ -17,7 +17,6 @@
 package live
 
 import (
-	"encoding/csv"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -36,20 +35,21 @@ func init() {
 }
 
 type perfTracerConfig struct {
-	CSVPath string `json:"csvPath"`
+	Path string `json:"path"`
 }
 
 // perfTracer is a live tracer that measures and records transaction processing performance metrics.
 // It tracks total processing time, IO time (account and storage reads), and EVM execution time for
-// each transaction. The metrics are written to a CSV file.
+// each transaction. The metrics are written to a JSONL file.
 type perfTracer struct {
-	csvPath string
-	writer  *csv.Writer
+	path    string
 	file    *os.File
+	encoder *json.Encoder
 
 	// Block context
 	currentBlock     *types.Block
 	currentBlockHash common.Hash
+	blockStartTime   time.Time
 
 	// Transaction tracking
 	txStartTime time.Time
@@ -59,6 +59,9 @@ type perfTracer struct {
 	prevAccountReads time.Duration
 	prevStorageReads time.Duration
 
+	// Transaction data collection
+	txData []map[string]interface{}
+
 	statedb tracing.StateDB
 }
 
@@ -67,36 +70,20 @@ func newPerfTracer(cfg json.RawMessage) (*tracing.Hooks, error) {
 	if err := json.Unmarshal(cfg, &config); err != nil {
 		return nil, fmt.Errorf("failed to parse config: %v", err)
 	}
-	if config.CSVPath == "" {
-		return nil, errors.New("csv path is required")
+	if config.Path == "" {
+		return nil, errors.New("path is required")
 	}
 
-	// Open CSV file
-	file, err := os.OpenFile(config.CSVPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	// Open JSONL file
+	file, err := os.OpenFile(config.Path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
-		return nil, fmt.Errorf("failed to open CSV file: %v", err)
-	}
-	writer := csv.NewWriter(file)
-
-	// Write header if file is empty
-	info, err := file.Stat()
-	if err != nil {
-		file.Close()
-		return nil, fmt.Errorf("failed to get file info: %v", err)
-	}
-	if info.Size() == 0 {
-		header := []string{"block_number", "block_hash", "tx_index", "tx_hash", "total_time_ns", "io_time_ns", "evm_time_ns", "gas_used"}
-		if err := writer.Write(header); err != nil {
-			file.Close()
-			return nil, fmt.Errorf("failed to write CSV header: %v", err)
-		}
-		writer.Flush()
+		return nil, fmt.Errorf("failed to open JSONL file: %v", err)
 	}
 
 	t := &perfTracer{
-		csvPath: config.CSVPath,
-		writer:  writer,
+		path:    config.Path,
 		file:    file,
+		encoder: json.NewEncoder(file),
 	}
 
 	return &tracing.Hooks{
@@ -112,6 +99,8 @@ func (t *perfTracer) OnBlockStart(event tracing.BlockEvent) {
 	t.currentBlock = event.Block
 	t.currentBlockHash = event.Block.Hash()
 	t.txIndex = 0
+	t.txData = make([]map[string]interface{}, 0)
+	t.blockStartTime = time.Now()
 	// Reset previous IO measurements for the new block
 	t.prevAccountReads = 0
 	t.prevStorageReads = 0
@@ -143,36 +132,49 @@ func (t *perfTracer) OnTxEnd(receipt *types.Receipt, err error) {
 		evmTime = totalTime - ioTime
 	}
 
-	row := []string{
-		t.currentBlock.Number().String(),
-		t.currentBlockHash.Hex(),
-		fmt.Sprintf("%d", t.txIndex),
-		receipt.TxHash.Hex(),
-		fmt.Sprintf("%d", totalTime.Nanoseconds()),
-		fmt.Sprintf("%d", ioTime.Nanoseconds()),
-		fmt.Sprintf("%d", evmTime.Nanoseconds()),
-		fmt.Sprintf("%d", receipt.GasUsed),
-	}
-	if err := t.writer.Write(row); err != nil {
-		fmt.Printf("Failed to write CSV row: %v\n", err)
+	txRecord := map[string]interface{}{
+		"txIndex":   fmt.Sprintf("0x%x", t.txIndex),
+		"txHash":    receipt.TxHash.Hex(),
+		"gasUsed":   fmt.Sprintf("0x%x", receipt.GasUsed),
+		"totalTime": fmt.Sprintf("0x%x", totalTime.Nanoseconds()),
+		"ioTime":    fmt.Sprintf("0x%x", ioTime.Nanoseconds()),
+		"evmTime":   fmt.Sprintf("0x%x", evmTime.Nanoseconds()),
 	}
 
+	t.txData = append(t.txData, txRecord)
+
 	t.prevAccountReads = accumulatedIO.AccountReads
 	t.prevStorageReads = accumulatedIO.StorageReads
 	t.txIndex++
 }
 
-// OnBlockEnd implements tracing.BlockEndHook
 func (t *perfTracer) OnBlockEnd(err error) {
-	if t.writer != nil {
-		t.writer.Flush()
+	// Calculate block-level timings
+	totalTime := time.Since(t.blockStartTime)
+	blockEndIO := t.statedb.GetAccumulatedIOMeasurements()
+	ioTime := blockEndIO.AccountReads + blockEndIO.StorageReads
+	evmTime := totalTime - ioTime
+
+	blockRecord := map[string]interface{}{
+		"blockNumber":  fmt.Sprintf("0x%x", t.currentBlock.Number()),
+		"blockHash":    t.currentBlockHash.Hex(),
+		"gasUsed":      fmt.Sprintf("0x%x", t.currentBlock.GasUsed()),
+		"totalTime":    fmt.Sprintf("0x%x", totalTime.Nanoseconds()),
+		"ioTime":       fmt.Sprintf("0x%x", ioTime.Nanoseconds()),
+		"evmTime":      fmt.Sprintf("0x%x", evmTime.Nanoseconds()),
+		"transactions": t.txData,
+	}
+
+	if err := t.encoder.Encode(blockRecord); err != nil {
+		fmt.Printf("Failed to write block record: %v\n", err)
+	}
+
+	if t.file != nil {
+		t.file.Sync()
 	}
 }
 
 func (t *perfTracer) OnClose() {
-	if t.writer != nil {
-		t.writer.Flush()
-	}
 	if t.file != nil {
 		t.file.Close()
 	}